In the Logos Blog, in the FAQ section concerning the Logos Chrismas Sale, here's the 1st Q & A re: the sale of the 2,010 titles -
Is there a way I can see what I already own?
Yes. All 2,010 titles in the master collection are also available for sale in our new Christmas Specials list. You can either filter out the titles you already own to see what’s left, or filter out the titles you don’t own to see what you have. This should help you evaluate how much of the content (if any) you already own and find the collection(s) that are best for you.
Does someone know how you can filter out the titles you already own to see what's left, or filter out the titles you don't own to see what you have?