Yes, no, sort of.

TCP and UDP just signify the protocol being used by whatever service/daemon is running on the port. There is no reason that either couldn't be used on a port, but as I understand it a service/daemon can only use one at a time. A normal service/daemon, that is (FTP, sendmail, whatever). I think you could write a service/daemon that would use both, I don't know if any currently do though. I'm sleepy. I'm going to bed.

Good night everybody... I hope this made sense, I'll read it in the morning and fix it.