[Guest]

The packard Merlin is just a sound file. The Spitfire and the Mustang use the Merlin engine, both use the same sounds, pointless having more files than needed.

The Packard Merlin, and the Rolls Royce Merlin sound different Wolf. It might not be so obvious in moddern day aircraft because some spits have have packards and vise versa due to availability. But there is a difference if you listen carefully