Quite simply, what known official game, as in a decisive tounament game, holds the record for the most double-steps by pawns? The most I have found, in quite a few games, is 8. As an example, below is a game in which all 8 double steps occur in just 15 moves. Computer games of any kind are not to be considered.
[Title "John Cochrane-Bonnerjee Mohishunder, Calcutta, 1855"] [FEN ""] 1.e4 e5 2.Nf3 Nf6 3.Nxe5 d6 4.Nxf7 Kxf7 5.Bc4+ Be6 6.Bxe6+ Kxe6 7.O-O Kd7 8.d4 Kc8 9.c4 Nbd7 10.Nc3 Kb8 11.f4 a6 12.a4 Ka7 13.b4 Rc8 14.Be3 Kb8 15.a5 c5 16.b5 Ka7 17.d5 g6 18.Qb3 Bg7 19.Rfb1 Rb8 20.b6+ Ka8 21.Nb5 Ne8 22.Ra2 Rf8 23.Na7 Ndf6 24.Nc6 Qd7 25.Nxb8 Kxb8 26.e5 Ng4 27.e6 Qe7 28.Kh1 Qh4 29.g3 Qh3 30.Bg1 g5 31.Qa4 Nef6 32.e7 Rc8 33.fxg5 Ne4 34.Rg2 Nc3 35.e8=Q Nxa4 36.Qxa4 Rf8 37.Re1 Be5 38.Qb3 Kc8 39.Qd3 Kd7 40.Rf1 Ke7 41.Rxf8 Kxf8 42.Qf5+ Kg7 43.Qd7+ Kg6 44.Qxb7 Bd4 45.Bxd4 cxd4 46.Qc6 d3 47.Qxd6+ Kxg5 48.Qf4+ Kg6 49.Qe4+ Kg7 50.Qxd3