RP6 with dual screen add on - 120 v 60hz?

After seeing a post that you can actually get the screen centered with different cables (2 of these https://a.co/d/0aB6eRGi and https://www.amazon.com/GHQXZT-Female-Extender-Compatible-Thunderbolt/dp/B0F2MN9V5Q)

I'm now considering buying the dual screen add on as I have a couple ds and 3ds games I want to explore. I'm aware it's clunky and ayn thor exists.

Anyway, with the different screen refresh rates, does that end up looking strange in practice? Is there a fix to just set both to 60? Thanks