Jobs are fetched LIFO and not FIFO from a queue

[wertzui]

In our setup we are using MAMQ with SQL Server as backend storage.
We recently had a situation where Jobs where enqueued faster than they could be processed leading to an increasing queue of jobs.
We observed that jobs where in the queue for multiple hours, while recently enqueued jobs would get fetched and processed.

So the queue seems to be a stack (LIFO), rather than a queue (FIFO).
Is there anything to ensure that the oldest jobs in the queue get fetched an processed first?