Robin Cassady makes a
mounting adapter to compensate for this, although it isn't cheap. Greg Bock uses what I think is a home-made mounting plate that achieves the same result, if you ever get a chance to see his setup.
You can shim the mounting plates on the scopes with any of a number of objects, but of course there is a lot of trial and error involved without something that is designed to be both adjustable and rigid.
I just live with the error myself at this point, but some time would like to get an adjustable base plate.