I will add a check for a blank ID.
As for the filters, they don't work when the dupe check is used, it really should not be included in the filters but I wanted to have the list browseable unlike previous versions which just returned a text list.
TBH the filters need a bit of work, im just building myself up, the routines dealing with the filters are getting overly complex. It may be time to split and simplify.
As for finding dupes, they should be listed in pairs.
I will also look into adding the actor search, to be honest I forgot about it.