The composer's intended solution is as above (and it contains duals - BDS).
Regrettably, the following first moves also
solve the problem, in some cases in four moves: 1.Bxe5 1.Sxe5 1.f3 1.Sf6 1.Rb7 (and 1.Bb2 - BDS)
In accordance with the rules of the contest, full points plus a bonus were awarded to
competitors giving one correct solution and at least one further correct solution.
4. Composer?
Source?
Selfmate in 2
1.Ke5! ()
1...Kxc7 2.d8=Q+ Kxd8#
1...Rxc7 2.d8=S R any#
1...Sxc7 2.Kf4 S any#