M6 Oil Filter on a M5?

[DiscoStew]

Had the first oil change (5k) on the M5. The shop didn't have the correct filter # in the computer, as a result they said they used a filter specified for the M6 and it fit perfectly. Should I be worried about this? Do they both have a 2.3 engine? A M3 filter would seem to have been more logical to me as a reasonable replacement.

Thanks!

- Stew