Call Leupold customer service and they will probably send you the one you need for free if you explain what happened.
I'm a big fan of dual dovetail scope mounts. They don't have the windage adjustments like the standard mounts with nothing to come loose or get knocked out of whack.
I called Leupold customer service and explained that I love the dual dovetail mounts and they no longer catalog them, and that I hate to spend the cash on 2 sets only to throw the rears away. I also explained that I had already purchased one of the standard sets because that's what I could find. They sent me another dovetail front base free that I installed on the rear and I wound up with a dual dovetail set. (These are pretty far apart so will only work on a scope with a fairly long tube) They were perfect for mounting a Bushnell elite 3200 onto my model 110FP long action and are rock solid.
They gave me great customer service and I'm sure they would do the same for you.