I know there's already plenty of fixes around, but they don't work when your Dreadnaught ship is full of duplicated crew.

hey just posted this responding to you in the main forum for the mod so I'll post it again here. Basically, it's a vanilla game bug, so don't worry it wasn't the mod that did it! Here's what I posted that has a workaround for now:

Hey guys fellow mod user here, the duplication bug is a vanilla game bug, so StarBound developers have to fix it. It is definitely super annoying though. Workaround for now: dismiss the target crewmember and it will remove one duplicate. Interact with another copy to get the crewmember back on the list and then continue to do those steps until you're left with one of that crewmember. For tailor's you have to dismiss one and then use lava to get rid of the copies because you can't interact with them after. Which means you have to completely get rid of the tailor you have at the time. :-( Hopefully Chucklefish fixes it soon.

I know the workaround is currently tedious, but it's the only method that I've done to clear up my crew when the bug happens, and it will probably happen multiple times until it's fixed.

Another workaround is any sort of damage that counts as indiscriminate. Such as from some of the XS mechs. Melt your crew members with "freakin laser beams."

Nice! I didn't think of that. Good idea. :-) I haven't tried that one myself but I don't see why they coudln't work. Be careful with those mechs though, they'll put a hole in just about anything lol