So for some reason ever since this morning when I switched FPP from blacklist props to whitelist props, ADV dupe has not been working.
Looked through the code and didn’t find anything, so I must be blind ( and obviously in need of someone much smarter than I )
Whenever you try to paste with adv dupe it says “this model is not in the whitelist” ( a message from FPP )
found the issue; turns out adv dupe spawns “models/props_lab/labpart.mdl” whenever you paste. added that to whitelist and good to go!