They don't. I have downloaded several lots and even my own and the ones that have objects overlapping always deletes all of the furniture (except stuff hanging on the walls). I just removed the mod earlier and found that there wasn't much overlapping. About 7 things ended up in my inventory, but the good news is that I can place the lots between saves and just a few things have changed. The idea of the mod is awesome, but it just isn't working out. Many people have mentioned the problems at MTS.