1. Selecting - Duplorcator's selecting is completely broken. Try building something on 64x64 baseplate. When you try to dupe it without the baseplate, it selects it too, and everything else.
2. Relays events are broken - self explanatory, they're broken
3. Duping default doors leads to wtf stuff - weird blank and disabled events get added to doors
4. Some events just flat out don't dupe
and that client load system is flat out broken, although the old dupe didn't have it either.
Old duplicator issues:
1. Lots of City RPG issues