There is a workaround.
Create a new group called XY
- Batch update X users to that group XY
- Batch update Y users to that group XY
XY now has some users from X some from Y and some from both.
You now need to remove those with just X or just Y and keep those with both.
- Do a batch update for all users in XY who are NOT in X and remove them from XY
- Do a batch update for all users in XY who are NOT in Y and remove them from XY
XY now cuts has users in X AND Y