I'm inclined to think that the frame on German eBay (which does look like the same one Matthew Brown provided the link to that sold as a complete bike) is neither a Kessels Merckx nor a Falcon Merckx.
I am surprised that your other Kessels would have an Italian BB, but I know very little about Kessels--except for having looked at some of the "Merckx" line while puzzling over Falcons.
I can say have never seen lugs with those round cut-outs nor those long bb cutouts on a Falcon frame--and in general the high-end "Falcon" and "Merckx" were virtually identical except for paint, decals and occasionally minor component variation.
Dean Kernan
Pomona, New York USA