thomastonk: I don't think that the recent change from "Blackburne / H Chapman vs Boulaye, 1880" to Blackburne vs Chapman / Boulaye, 1880 was an improvemont. Instead, I believe that this game and all games listed above as "Blackburne / H Chapman" and dated before 1895 were played by Blackburne alone. There are several reasons therefore, one of them being that they all can be found in "Blackburne's Game at Chess" without a mention of Chapman.
Blackburne / H Chapman vs NN, 1862 is game no 251 on page 214, as Blackburne vs Amateur, Manchester 1862. It was one of only 4 games he played in his first public blindfold exhibition, as he wrote. Here it is again: Blackburne vs NN, 1862, but there "BFX" indicates a 10-board blindfold, I guess.
Blackburne / H Chapman vs NN, 1871 is game no 279 on pages 232-233, as Blackburne vs Amateur, Manningham 1871, played in a 8-board blindfold.
Blackburne / H Chapman vs B Cockayne, 1873 is game no 289 on pages 238-239, as Blackburne vs B.Cockayne, Sheffield 1873, played in a 10-board blindfold.
Blackburne / H Chapman vs NN, 1875 is game no 311 on page 254, as Blackburne vs Amateur, Bradford 1875, played in a 8-board blindfold.
Blackburne / H Chapman vs Philp, 1875 is game no 156 on pages 154-155, as Blackburne vs Philp, London Chess Club 1875.
Probably, someone, who collected King's gambit games from that book, made a copy&paste error.