Just to let you know, I gave this beta version a try and it allowed duplicate downloads. It also trashed/deleted the duplicate database, which was rather large and very old. I've reverted to the current working version and duplicates are now being blocked. I'm on Win 8.1 64 bit if that helps.
I think I'll avoid beta versions from now on.
Dunno if this post should be in a Beta discussion, but I logged on and was blocked from using going there.