In both cases, there are 2 jpg (or, in the case of BTO…bmp) pics. One is called folder; the other is inside a subfolder called Art. The 2nd file is not duplicated in either case. In neither case is the folder.jpg or folder.bmp embedded in the metadata. In both cases (see screencaps) Roon shows a total of 3 available pics to look at, and #'s 1 and 3 are duplicates of each other.
I have this problem for pretty much all my albums. Hope the bug gets sorted soon! Also hope that extra artwork features are soon added such as delete within Roon, re-order artwork, name artwork etc.