This is very useful, thank you.
I have no idea how to make the URLs, sorry, but if someone wants to be a completionist there are some older simultaneous videos that aren't videogame recordings:
https://www.giantbomb.com/videos/brad-loves-mondays-043012/2300-5933/ & https://www.giantbomb.com/shows/the-real-i-love-mondays-04302012/2970-18093/ are competing recordings by Brad and Ryan
And it's maybe not a great fit because it's so short, but https://www.giantbomb.com/shows/giant-bomb-mailbag-11172011/2970-17975 overlaps with https://www.giantbomb.com/shows/quick-look-kinect-disneyland-adventures/2970-14575 (~3 minutes into the first, and ~7:20 into the quick look) for barely a minute.
I'm not an insane person with some kind of super memory, I just keep a long long list of GB videos I like (maybe that's a little crazy) and the duplication was amusing enough when I watched them that I made a note of it.