First, why do you want another remote? If it's because the buttons don't work on your old one, this could be one of two things: the battery tabs have come loose and need to be resoldered (easy job for someone with a soldering iron, or take it to a Batteries Plus store Ive heard). OR the rubber membrane is breaking down or dirty - clean it or buy a cheap replacement off ebay (<$5).
If you fix your original you won't need to get it reprogrammed. But if you buy a replacement, then ONLY the dealer can reprogram it (as Hoosier says, take all your remotes together).