I'm aware I can just GM fiat it if I like, but I'm curious to know if in the rules-as-written there exists language that prevents Tom's ghost from existing at the same time as Tom's animated skeleton also exists. In the homebrew I'm running, I had the idea that Tom's ghost wants the party to slay Tom's skeleton and properly bury his remains — his unburied and animated remains being the reason the ghost formed and persists.
James Jacobs (Paizo's Creative Director) says you can create zombies from the corpses of creatures that turned into a ghost:
Can you make a new zombie/skeleton from the remains of a defeated zombie/skeleton?
Can you make a ghost(or other incorperal undead) and still make a zombie or other unintelligent undead of the corpse?
Can you make a ghost(or other incorperal undead) and still make a ghoul or other intellgent undead? if not will the ghost be pulled in to the body to provide the intelligents for the body or will it just not work?
Which actually makes a lot of sense, ghosts are described several times as disembodied undead on the Classic Horrors Revisited campaign setting. Though no specific ruling is given about whether or not you can turn a ghost's former body into another type of (corporeal) undead creature.