Double Zilahi
There are four thematic pieces. A and B are captured and give mate in two phases. C and D are captured and give mate in two other phases. C and D can be the same pieces as A and B. In fact, double Zilahi is two unrelated pairs of phases with simple Zilahi.
See also: Zilahi; Cyclic Zilahi.
Babic, Milomir
Problem-Echo TT, 1997
2nd Prize
h#3 2.1... (3+16)
b) bPa5→e6
a)
1.dxe1=Q
Bxd3
2.Qb4
Bf5
3.Qb6
Bd7#
1.axb1=R
Rxe5
2.Rb6
Re7
3.Bb5
Rc7#
b)
1.dxe1=B
Bxd3
2.Ba5
Bc2
3.Bb6
Ba4#
1.axb1=S
Re4
2.Sc3
Ra4
3.Sb5
Ra6#
Double Zilahi: R/B (2x).
Stucker, Bruno
Die Schwalbe, 1989
1st Prize
h#2 (7+6)
b) bPg4→g5
c) bKf4→h3
d) +bPf5
a) 1.Rxe7
Sf1
2.Re4
Rf6#
b) 1.Bxb6
Sh2
2.Be3
Bd6#
c) 1.Bxg3
Rb2
2.Qg1
Sxg1#
d) 1.gxf3
Re6
2.Rg4
Sh5#
Double Zilahi: R/B and S/S.