Hey thanks! I've uploaded it to google drive for you to take a look at when you can:

https://drive.google.com/open?id=0B-456TmJeWeZRDBpSmdnUHl3emc

I did make a test level in that mod and added the same chair along with the broken version, and when I load that level in DM mode both items appear, so it does seem like the problem is limited to that particular level.