from the forum thread.
Picard should be able to fetch both PUID and AcoustID before trying to match them against MB data.
Once both fetched and put into tags we can still keep this priority setting to tell Picard which ID to try to match first (but we add a fallback to the other one).

It means that in the current fingerprinting system, the radio button would designate the preferred fingerprint used for matching on MB. Let's say we selected AcoustID :

Hitting scan button would do for each file

1. Launch both PUID and AcoustID requests, grey the file
2. When both PUID and AcoustID responses are back, set PUID and AcoustID tags with found stuff and ungrey the file
3. Search for an AcoustID match on MB (preference setting)
   1. If none matched, search for a PUID on MB