My personal take is that Pratt achieved five victories:
15-Feb-1917: 2nd-Lieut
Stuart Harvey Pratt & 2nd-Lieut Geoffrey Bryers, 46 RFC, Nieuport 20 A229, Albatros Scout captured [+ 1 RFC] Vlamertinghe at 17:00/18:00
25-May-1917: Capt Stuart Harvey Pratt, 46 RFC, Pup A7327, Albatros out of control
03-Jun-1917: Capt Stuart Harvey Pratt, 46 RFC, Pup A7327, Albatros Scout out of control Quesnoy at 08:30/09:30
15-Jun-1917: Capt Stuart Harvey Pratt, 46 RFC, Pup A7327, Albatros C out of control ? Ploegsteert at 10:50/11:50
17-Jun-1917: Capt Stuart Harvey Pratt, 46 RFC, Pup A7327, Albatros Scout out of control Lens at 19:30/20:30
The listing on this Forum suggests a victory in March 1917 and another on 5 June 1917.
I have nothing for Pratt in March 1917 and the combat report for 5 June 1917 reads (verbatim):
Capt Pratt had three fights but gun was not satisfactory owing to connecting rod working loose. He attacked one two seater over Wytschaete fired few rounds but had to desist owing to gun. Attacked single seat Albatross over warneton but had to give up al so owing to gun. Attacked third two seater over Armentieres but gun was still poor and no result was observed. H.A. retired.
The report gives the names of the nine pilots involved but no serial numbers.
I am tempted to believe that the 5 June 'claim' is actually a mis-dated duplicate of the 3 June claim.
Graeme