Guids in custom.json only uses ratingKey from a single instance

[ShanaryS]

If there is the same movie/show in multiple libraries, when using guids in custom.json, it only works on one of them, at least for blocking with tvdb://.

[mdhiggins]

This is going to require a decent amount of work to fix, for now if you have the same content duplicated in multiple libraries I would just use the ratingKey and copy the entries, I'll try and get this fixed though