Helpmate in 2 (2 Solutions)

If Black were allowed to waive the first move, then 1.pass b3+ 2.Ka5 Nc6# and 1.pass Bc5 (d6/e7/f8) 2.Ra5 b3# would constitute two solutions. However, these are only ‘tries,’ each failing for lack of a suitable tempo move for Black’s first turn.

The actual solution-pair is 1.Rb4 (tempo) Ka6 2.Rb3 axb3# and 1.Rc5 (tempo) Ne2 2.Ra5 Nc3#, both beginning with tempo moves and concluding in a very different set of mates from those in the tries.

One could say the problem presents four h#1.5 sequences: two without any possible B1 tempo moves, and two with unique B1 tempo moves — a fine achievement!