engine sound bug? or oversight

as someone who does not like the sound of modern F1 engines i like to substitute the official engine sounds with my own which is how i discovered what appears to be a bug perhaps or an oversight by codemasters/EA

in the game mercedes, aston martin, and audi are listed as having their own engines

mercedes uses mercedes engine

audi uses audi engine

aston martin uses honda engine

however if you change the mercedes engine file with another it also replaces the sound of the aston martin and the audi engine to the same sound indicating that this is either a bug or that for some reason both aston martin and audi are using the mercedes engine which they should not be doing