Updating entry w NEO field results in exception "Attempting to duplicate an unsaved element"

[mach1media]

Description

Updating existing entry with NEO field produces yii exception "Attempting to duplicate an unsaved element."

vendor/craftcms/cms/src/services/Elements.php at line 734

Steps to reproduce

1. Create new entry with NEO field and SAVE
2. UPDATE entry with NEO field making one small change to any field

Other information

Application Info

PHP version 7.3.9
OS version Darwin 19.5.0
Database driver & version MySQL 5.7.26
Image driver & version GD 7.3.9
Craft edition & version Craft Pro 3.4.21
Yii version 2.0.35
Twig version 2.12.5
Guzzle version 6.5.4
Imagine version 1.2.3-dev

Plugins

Config Values Field 1.0.0
Entry Instructions 1.0.7
Freeform 3.6.9
Image Resizer 2.0.9
Matrix Toolbar 1.0.6
Neo 2.7.12
Obfuscator 1.0.4
Position Fieldtype 1.0.14
Redactor 2.6.1
Redactor Tweaks 2.0.4
SEO 3.6.5.1
Super Table 2.4.9
Table Maker 2.0.1
Video Embedder 1.1.4

• Is eager-loading used? YES

[ttempleton]

Closing this issue as a duplicate of #352.