I'm setting up 2 scsi drives,I have a dual port adaptor.My question is;should I set one drive on each port or just chain them on the same port?

Well, that's a loaded question! :p There's more to SCSI than just that. I would say that if you have a SCSI card that can just do looped termination, then put them each on their own port. If it's a really old version of SCSI, it probably won't matter because the drives aren't that good! ;)