Duplicate devices (2x MX Master 3's in my case) show up separately, which is an improvement over the base Options software, however their settings are not individual.
For example, changing a keybinding on my own grey MX Master 3 immediately duplicates that same setting to the black one. The same works in reverse, and no matter what the binding of choice is.
Though a niche use case, I purchased the second device to use its own individual bindings in tandem with the first, however that isn't currently possible because of this software limitation.
As it is now, there's not much point to buying a duplicate device for any reason, so long as it runs through Options or Options+ because of this. I think it'd be quite obviously beneficial to work on such a distinction for both user and Logitech, in freedom and customization for the former, and increased potential sales for the latter.
I suspect it's already planned for the future - especially since both devices are now shown, rather than just a single one, but just in case, would it be possible to distinguish between identical device models connected at once, and allow them to be completely customized separate to one another?