bispanning graphs

Hello,

I recently stumbled upon bispanning graphs.
A bispanning graph is a graph G=(V,E) so that E can be partitoned into two sets P and Q so that (V,P) and (V,Q) are spanning trees of G.

Asking google for "bispanning graph" gives only a few results at the local chair. So either this graph class is actually quite exotic, or it is usually know by a different name.

Does anyone know about this kind of graphs?
What is the usual name for it?

Thanks,
Michael
.