I have both too, but my mini tanner is saddle brown and mini preston is black....that's how I avoided the 'too much alike' conflict. That being said, if you love both the bags and both in black, have both of them. Find another one on sale and go for it. Macy's and Dillards both have them marked down.
Bon Ton keeps putting the studded preston up on the web site and lets you order it and the almost immediately cancels the order. Preston disappears off the website for about 24 hours and they put it back up again. I ordered and got cancelled 3 times....each time they've gotten an increasingly nasty email from me. If they don't have any QUIT putting it back up on the website! Anyway, I ordered from elsewhere, cost me a little more, but at least I'm getting it and not a cancellation notice.