Duplicate Costume Ungroups All

[griffpatch]

Expected Behavior

Duplicating a sprite does just that, with no side effects

Actual Behavior

Vector costumes are fully ungrouped before the costume is duplicated ending up with two identical, but ungrouped costumes.

Steps to Reproduce

1. Draw two circles as a new vector costume.
2. Group them
3. Duplicate the costume
4. Check both costumes, them will both be ungrouped.

Operating System and Browser

Chrome, win 10

[thisandagain]

/cc @fsih @carljbowman