Group - Paste Aligned goes to Level Above

[lhanyok]

We are using a group for 4 curtain walls that repeat up a multistory building. When we try to use paste aligned with the group to levels above, it places it a level above where it should be placed (i.e. we paste aligned to Level 2, but it ends up on Level 3). When I save out the group, I end up with multiple levels in the file (first attachment).

I edited the group, and selected all the walls, cut, then paste aligned, but I'm still ending up with a level below that seems to be screwing things up (second attachment). I've tried searching here and elsewhere to no avail. Any ideas?

[lhanyok]

I tried deleting the extraneous levels in the group file. Then I loaded it back into the project and it seems to be fine.

So now, my question is more of how did this happen to make sure it doesn't happen again in the future?