Mismatched StarSpoke 212 Wheels

[monacoblue_x5]

Hi, first post here and it's about a problem I have.

Some information: I have the 2008 4.8i with Sport Package (20" RFTs Style 214) so my tires are staggered.

I purchased 19" Michelins M+S Tires on Style 212 wheels that were supposedly off a 2008 X6. The research I did prior to purchase indicated that the offsets were the same and these wheels would work. When I tried putting them on today, it appears I have 2 different pairs. The first pair were 'concave' at the hub, meaning the center of the wheel where the BMW logo is appears to round out (like an upside down bowl). The other pair were 'convex' at the hub. They (autoshop) could not even mount the convex pair on the hub. The concave pair fit on any 4 sides of the X5. The convex pair did not fit anywhere.

So my questions are:
1) Do the X6 have different offsets on the front and rears?
2) Did my 'good' deal turn out to be not so good and maybe I bought mismatched set?
3) If I order 2 new wheels from BMW, can I expect the correct set (I suspect I will get the right ones as I can return them if they're not).

Has anyone experienced this or can give me any additional insights?

I purchased these from an ebay 'consignment' store that was actually local here. I am trying to contact the seller to get some information but I have to go through the storefront. And yes, it was a sweet deal and if I do end up buying new wheels from BMW, I will have still saved money (but not time!)
Thanks.
Chris.