Callum
Disregard the initials as far as you can and concentrate on the other information. Most information in former days was hand written and any records now will have been transcribed from that handwritten information where-in the scribe may have had peculiaralities in his forming intials. I know my initials often appeared as I.S. and I.F. when in fact they are I.J. only my Discharge book number R611450 enable me to draw Pool pay and my father initials I.I. had the same trouble with his initials and only his Discharge Book R69069 allowed him to draw Pool pay, so go by the initials in his Discharge Book, as they will probably be the most accurate because your name(s) are written in full there-in.
Just a thought, Rgds Ivan
Good luck in your endeavours