Duplicated Assignment has submissions in the wrong spot

Sorry for the extremely vague subject - I will (try) explain in better detail here 

• We have a course set up with 4 separate groups and groupings
• The instructor created a set of assignments and assigned them to grouping 1
• He then needed a copy for grouping 2, so he duplicated the assignment that had grouping 1's students (and submissions) in there, and changed the grouping to grouping 2
• Some students who belong in grouping 1 have their submissions showing up in the duplicated assignment (grouping 2's) when you select "All users" from the drop down rather than the particular grouping
• Those few students submissions do not show up in the original assignment that was assigned to grouping 1

My guess is those three students used the duplicated version - created for grouping 2 - in the short time window when the assignment was created and the grouping was changed. Let's say there was a 2 minute window there - I think they submitted their assignments in that 2 minute window and that's why they are showing up in the wrong assignment activity.

Is there any way to move their submissions to the correct assignment?

Thanks a bunch!