Please help me start up with tags

[MiniMe]

I think I have the album sorting + playlist sorted with the following tagOptions:

album.sortTags={albumartist,Album},items.sortTags={albumartist,Album,title,Track​number}

I had issues with A-Z sorting of compilation Albums, that I resolved with AlbumArtist tagged into "VA"

Then, how does it come that if I browse e.g. to Genre, then go to Sorted by quality, that if I click the ' CD' option, that I get all items below 2x in the playlist? (I know that there below are a [n] items + cd1 + cd2 = together 2x all the items) But can I prevent this duplicate adding?