With b142 whenever new maps are made (the default of 2 is expanded for example) moving onto a new map and starting a new screen bugs out majorly with a bunch of garbage combos.
Edit: Screenshot of it. 
Strange bug when creating new maps (142)
this happened to me too, and it seriously destroys your work.
also, sometimes screens become "linked" as in if you make pallete or door changes in some rooms, things happen in another room somewhere else.
I got a temporary solution to getting around this until its fixed.
Export a blank map and then import it to the new map and it should work right again. Just so it doesn't put a halt on your testing
I think this is fixed now...
This bug is closely related to the undo bug and the paste all bug.
I believe these are all fixed, but watch for any strange behavior. My first couple of attempts to fix them almost worked, but had problems in certain cases (e.g. copying a screen, increasing the map count, and then pasting the screen on a new map would instead paste random combos). I'm pretty sure everything's okay this time, but be sure to post about any problems you see that seem to be related.