the two on the left are my S5 high compression rotors. The third on the right as spare from a 1989 that I was going to use as you can see the middle rotor has a depression cause possible by knock. Oddly the car ran fine and no broken seals. can I reuse this rotor?

Why the difference in rotors? I know the high compression ones were machined combustion centers but two of them looks like they were completely machined.

Thanks,
Ian

 

dent is from detonation.

the machining marks are from Mazda's machine needing a new bit, or maybe they stopped a final step or something.