Do I just need to bet them five times to get all of the loot that they will drop?

Pretty much, yeah. Like most opponents, they have a special drop on the fifth win, all the others give you junk items. They don't give anything really good like books or amulets, so there's no real reason to go past five wins unless you want the experience/sP/bragging rights.

thank you for the reply.I do not battle very much and I seem to always have some kind of question that seem not to important.