Chris Shores and Clive Williams' Aces High, which is the nearest thing there is to a 'bible of RAF 'ace' pilots' credits Pattle with around 50 victories and two shared, while Johnson is given 34 victories and seven shared.
As Biggus says, record keeping was a little lax in the Greek campaign (for obvious reasons...) and most of the paperwork was dumped into Piraeus (IIRC) Harbour during the evacuation. I think it's generally accepted, thanks to piecing together reports from Pattle's colleagues, that Pattle scored more than Johnson, and is a far less controversial issue than who the top-scoring RFC/RAF pilot was in WW1....