First off. the batch you display in your original posting in the screen shots is for batch 5054. (I'm dropping off the leading zeros in this reply).
You screen shots further down in your later reply that you highlight is 5057. I'm assuming this was a mistake and we are still talking about 5054.
So you received in 10 units of 5057. From you movements, I believe you posted 8 back to the vendor. You posted 2 to unrestricted inventory.
It appears you had a second posting that is not shown of 2 units from the inspection lot to UR. With the system set to allow negative inventory it allowed the posting. To be honest I've never seen this before.
What we need to see are the stock posting logs from the QM side. If you go into QA13 for the original inspection lot and select "Goto-->Stock Posting Log" I suspect you might find a second material document listed. It would however not be found in the MB51 list cause you'll find that the material document doesn't exist. It did at one time but something causes it to get cancelled but things aren't updated right.
Please provide a screen print of the stock posting log from the inspection lot. I think it will help explain things.
Craig