Carlos A. Grassano & Mario G. García - (Argentina)
 
#2 4+3

1.Qf1! - Qg1#  
1...f2 2.Qxh3#
1...Kg4 2.Qg1#;
1...Kh2 2.Rxh3#;
1...h2 2.Qxf3#
 
Two different w-units mate on the same square.