I think you just register once and they buy it for your shower and wedding. That's what we're doing for mine. I just registered at Dillard's, and if I get a wedding shower they work off the same registry.
I wouldn't register at Target; because I worked there as a manager, and I saw so many people who's registery wasn't done right because the checkers wouldn't do it right. I'd go to Dillard's or Macy's; JC Penny's has really pretty stuff too.
Good luck and have fun ! It's a blast getting to go register. We had a really nice lady at Dillard's help us out the entire way; I think she was bored and it gave her something to do, lol ... but we had fun.