Since you have mapped 1,2 keys to DECREASE, INCREASE prop pitch and this work fine for Bf 109, but not to Spit try this:
Go to Controls select INCREASE..., click in NEW (bellow, left side) and assign key 4.
Same for DECREASE... and assign key 3.
Use 1, 2 for Bf 109.
And 3, 4 for Spit.
Different planes/system, different keys. Now the key assignment are "logical", but HUD...
CloD allow multiple keys/buttons assignments to do the same control.
EDIT - If you use HOTAS and desire assign the pitch control in the same 2 buttons or HAT, in CloD controls save the first
assignement as Bf109 and the second as Spit... And load appropriated one before start fly in respective plane.
Sokol1