diff --git a/packages/react/src/components/ComboBox/ComboBox.js b/packages/react/src/components/ComboBox/ComboBox.js
index 89adac40f162..0c75d7947953 100644
--- a/packages/react/src/components/ComboBox/ComboBox.js
+++ b/packages/react/src/components/ComboBox/ComboBox.js
@@ -390,23 +390,26 @@ export default class ComboBox extends React.Component {
             {isOpen && (
               <ListBox.Menu aria-label={ariaLabel} id={id}>
                 {this.filterItems(items, itemToString, inputValue).map(
-                  (item, index) => (
-                    <ListBox.MenuItem
-                      key={itemToString(item)}
-                      isActive={selectedItem === item}
-                      isHighlighted={
-                        highlightedIndex === index ||
-                        (selectedItem && selectedItem.id === item.id) ||
-                        false
-                      }
-                      {...getItemProps({ item, index })}>
-                      {itemToElement ? (
-                        <ItemToElement key={itemToString(item)} {...item} />
-                      ) : (
-                        itemToString(item)
-                      )}
-                    </ListBox.MenuItem>
-                  )
+                  (item, index) => {
+                    const itemProps = getItemProps({ item, index });
+                    return (
+                      <ListBox.MenuItem
+                        key={itemProps.id}
+                        isActive={selectedItem === item}
+                        isHighlighted={
+                          highlightedIndex === index ||
+                          (selectedItem && selectedItem.id === item.id) ||
+                          false
+                        }
+                        {...itemProps}>
+                        {itemToElement ? (
+                          <ItemToElement key={itemProps.id} {...item} />
+                        ) : (
+                          itemToString(item)
+                        )}
+                      </ListBox.MenuItem>
+                    );
+                  }
                 )}
               </ListBox.Menu>
             )}
diff --git a/packages/react/src/components/Dropdown/Dropdown.js b/packages/react/src/components/Dropdown/Dropdown.js
index 13cc86180657..a217f085715e 100644
--- a/packages/react/src/components/Dropdown/Dropdown.js
+++ b/packages/react/src/components/Dropdown/Dropdown.js
@@ -185,6 +185,7 @@ export default class Dropdown extends React.Component {
         [`${prefix}--dropdown--inline`]: inline,
         [`${prefix}--dropdown--disabled`]: disabled,
         [`${prefix}--dropdown--light`]: light,
+        [`${prefix}--dropdown--${size}`]: size,
       });
     const titleClasses = cx(`${prefix}--label`, {
       [`${prefix}--label--disabled`]: disabled,
@@ -294,21 +295,24 @@ export default class Dropdown extends React.Component {
                 </ListBox.Field>
                 {isOpen && (
                   <ListBox.Menu aria-labelledby={id} id={id}>
-                    {items.map((item, index) => (
-                      <ListBox.MenuItem
-                        key={itemToString(item)}
-                        isActive={selectedItem === item}
-                        isHighlighted={
-                          highlightedIndex === index || selectedItem === item
-                        }
-                        {...getItemProps({ item, index })}>
-                        {itemToElement ? (
-                          <ItemToElement key={itemToString(item)} {...item} />
-                        ) : (
-                          itemToString(item)
-                        )}
-                      </ListBox.MenuItem>
-                    ))}
+                    {items.map((item, index) => {
+                      const itemProps = getItemProps({ item, index });
+                      return (
+                        <ListBox.MenuItem
+                          key={itemProps.id}
+                          isActive={selectedItem === item}
+                          isHighlighted={
+                            highlightedIndex === index || selectedItem === item
+                          }
+                          {...itemProps}>
+                          {itemToElement ? (
+                            <ItemToElement key={itemProps.id} {...item} />
+                          ) : (
+                            itemToString(item)
+                          )}
+                        </ListBox.MenuItem>
+                      );
+                    })}
                   </ListBox.Menu>
                 )}
               </ListBox>
diff --git a/packages/react/src/components/Dropdown/__snapshots__/Dropdown-test.js.snap b/packages/react/src/components/Dropdown/__snapshots__/Dropdown-test.js.snap
index 8432d797b7da..cdaf7d6a866c 100644
--- a/packages/react/src/components/Dropdown/__snapshots__/Dropdown-test.js.snap
+++ b/packages/react/src/components/Dropdown/__snapshots__/Dropdown-test.js.snap
@@ -353,7 +353,7 @@ exports[`Dropdown should render custom item components 1`] = `
                 id="downshift-4-item-0"
                 isActive={false}
                 isHighlighted={false}
-                key="Item 0"
+                key="downshift-4-item-0"
                 onClick={[Function]}
                 onMouseDown={[Function]}
                 onMouseMove={[Function]}
@@ -370,7 +370,7 @@ exports[`Dropdown should render custom item components 1`] = `
                   >
                     <itemToElement
                       id="id-0"
-                      key="Item 0"
+                      key="downshift-4-item-0"
                       label="Item 0"
                       value={0}
                     >
@@ -387,7 +387,7 @@ exports[`Dropdown should render custom item components 1`] = `
                 id="downshift-4-item-1"
                 isActive={false}
                 isHighlighted={false}
-                key="Item 1"
+                key="downshift-4-item-1"
                 onClick={[Function]}
                 onMouseDown={[Function]}
                 onMouseMove={[Function]}
@@ -404,7 +404,7 @@ exports[`Dropdown should render custom item components 1`] = `
                   >
                     <itemToElement
                       id="id-1"
-                      key="Item 1"
+                      key="downshift-4-item-1"
                       label="Item 1"
                       value={1}
                     >
@@ -421,7 +421,7 @@ exports[`Dropdown should render custom item components 1`] = `
                 id="downshift-4-item-2"
                 isActive={false}
                 isHighlighted={false}
-                key="Item 2"
+                key="downshift-4-item-2"
                 onClick={[Function]}
                 onMouseDown={[Function]}
                 onMouseMove={[Function]}
@@ -438,7 +438,7 @@ exports[`Dropdown should render custom item components 1`] = `
                   >
                     <itemToElement
                       id="id-2"
-                      key="Item 2"
+                      key="downshift-4-item-2"
                       label="Item 2"
                       value={2}
                     >
@@ -455,7 +455,7 @@ exports[`Dropdown should render custom item components 1`] = `
                 id="downshift-4-item-3"
                 isActive={false}
                 isHighlighted={false}
-                key="Item 3"
+                key="downshift-4-item-3"
                 onClick={[Function]}
                 onMouseDown={[Function]}
                 onMouseMove={[Function]}
@@ -472,7 +472,7 @@ exports[`Dropdown should render custom item components 1`] = `
                   >
                     <itemToElement
                       id="id-3"
-                      key="Item 3"
+                      key="downshift-4-item-3"
                       label="Item 3"
                       value={3}
                     >
@@ -489,7 +489,7 @@ exports[`Dropdown should render custom item components 1`] = `
                 id="downshift-4-item-4"
                 isActive={false}
                 isHighlighted={false}
-                key="Item 4"
+                key="downshift-4-item-4"
                 onClick={[Function]}
                 onMouseDown={[Function]}
                 onMouseMove={[Function]}
@@ -506,7 +506,7 @@ exports[`Dropdown should render custom item components 1`] = `
                   >
                     <itemToElement
                       id="id-4"
-                      key="Item 4"
+                      key="downshift-4-item-4"
                       label="Item 4"
                       value={4}
                     >
@@ -685,7 +685,7 @@ exports[`Dropdown should render with strings as items 1`] = `
                 id="downshift-3-item-0"
                 isActive={false}
                 isHighlighted={false}
-                key="zar"
+                key="downshift-3-item-0"
                 onClick={[Function]}
                 onMouseDown={[Function]}
                 onMouseMove={[Function]}
@@ -708,7 +708,7 @@ exports[`Dropdown should render with strings as items 1`] = `
                 id="downshift-3-item-1"
                 isActive={false}
                 isHighlighted={false}
-                key="doz"
+                key="downshift-3-item-1"
                 onClick={[Function]}
                 onMouseDown={[Function]}
                 onMouseMove={[Function]}