Probably because only a few survive, makes them rare and they are a unique in the fact and I can't recall another 2 cylinder push mower, probably there is but I don't know of them
Trouble is, they behave like a single cylinder anyway. Would have been more practical to have a single cylinder 170cc, but where is the hype in that?
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!