Never heard about the 10-device limit, but I guess it could be a thing. But this…
One strange thing is that Renoise tends to list most devices twice… Not sure if that’s anything to worry about, but it’s never really gotten in my way previously.
That surely shouldn’t happen. The first thing I would do is to check is whether other softwares with MIDI input report the same number of ports. That would perhaps indicate whether the problem exist in Renoise or is somehow related to your operating system.
But otherwise, yeah you might have stumbled upon a bug. I know another one fixed in which multiple (legit) devices registered under the same name, but this is kind of the opposite problem.