Just got back and read your post, quisling, thanks.
Perhaps I'm still not getting it because I can't quite see the connection. Here's where I am at the moment -
I knew of that link and quite liked the original US show but only one of that particular 'double act' appears to be correctly named - shouldn't both be short versions? And why the oblique ''/'' in the space provided?
And how do both titles together illustrate the puzzle gimmick?
My original search for 'double acts' failed on the bottom right in a similar way because it lacked the necessary shortening (although in full, it matches one of a 60s pop duo). Similarly, the top one is only one half of a US partnership in a completely different field. My thinking is that on one half of the grid someone is missing - on the other side they're both there. The clue gimmick led me to think of an entirely different kind of 'double act' that might account for this (and it is separated by an ''/'').
This won't be the first (or last!} time I've overcomplicated an endgame but I think I'll need a bigger nudge to push me in another direction. Hope my latest 'soliloquy' isn't quite as tortuous as my last one and you can see what I'm getting at (it's quite difficult to discuss these things in the abstract).