Okay, now you know why I try to avoid releases of Rhino Mocks, every time I make a release, I usually have a week of sudden activity, with new features / fixes coming in.
This time it's a regression that happened with regard to generic types. The issue is that you can't mock any generic type more than once. I had tests for mocking generic types, but I didn't have any tests for trying the same type multiply times.
Well, now I do, and it's fixed. So you can go ang get sources and binaries from this page.