Things of note while dual wielding in this manner. Using them both on a single target is quite easy, there's little to no indication that it's any different from a single gun firing at double rate when you can see the round impacts. However, it gets marginally harder within the front cone of view and no longer on a single target. Do do this, you unfocus your eyes to bring all targets into equal mental consideration. GURPS terms, I'd say it's a -1 within Tunnel Vision range, and a -1 to checks to identify specific targets. Out a little wider, I'd say it goes up to an additional -1, and further -2 for target ID when something moves into the field of view you're watching.
That said, I definitely want a matched pair of somethings.
Glock 17 Gen 4. I already have one, and you can switch the mag release to the other side for lefty use.
Glock 34, I'd need a pair, and probably go for custom engraving while I was at it. I want a gen4 34 eventually anyway, because longslide.
.22lr something. They're marginally cheaper than most full on handguns, and far easier to feed (in theory, anyway. Can we buy .22lr again? I haven't seen it in ages).
PLR-16s, piston drive AR-15s in .300 blk, or something in 5.45 or 7.62 x39 like a Krinkov or Draco pistol. They're light, enormous, and ridiculous, all of which are perfect.
PLR-22. All the ridiculousness of above, but with the theoretical ease of feeding of .22lr.
Super Redhawk .454 with 10" barrels. These, in custom made show leather holsters, would be my guns for open carry were I ever to do so. I have a lot of the gunslinger aesthetic about how I dress, so it makes sense, also big magnums because again, ridiculousness is mandatory (and I can keep control of a magnum one handed with very little difficulty)