I added quite a lot of ISRCs over the last weeks. Before adding them to a release, I usually check for existing ones. Personally I don’t like to add a different ISRC to an existing recording. So I am not happy about examples like this: http://musicbrainz.org/recording/10cfdacf-53c3-4662-b216-62046e318f6e
According to the Style guidelines, recordings with different mastering should not be separated. The guidelines for edits are less straightforward. Should we merge similar edits if they are only distinguishable by ISRC?