I'm curious if the USB B port from the Montage can be split into two USB A cables?

No

If this would work it would allow me to not have to re-plug the keyboard USB every-time I change computers.

Not a big deal. I’m sure if you threw enough money at the issue you could find a solution... but a simple “y” cable is not a possibility. The MONTAGE USB connection is carrying both Audio and MIDI: 32-audio bus outs, 6-audio bus returns and the equivalent of 6 MIDI cables... you can’t just simply split that so it does double that, no.

I know Cubase Pro (and software of that level of sophistication can be configured into systems that connect to multiple computers) you may want to reach out to Steinberg if this is an important function for your situation. Once configured it would stay in place (I’m guessing).

I personally do not have that 2 computer thing in my wheelhouse, and as you know that is an area that is on ever shifting ground... with Mac computer OS’s making a major change... this could improve/worsen the situation or it certainly is worth getting in the loop as everybody jumps to the ‘new’ rules. I would recommend reaching out to Steinberg, if this is something you want to seriously configure.

Hope that helps. If you have a MONTAGE, you have access, through your MySteinberg Account, to those on the front lines of the computer situation.

I’m using one of these with the USB-B input of my Montage. I’m using it to switch the output of a MIDI controller keyboard between either the Montage or a USB hub connected to my PC.

I am not sure if it would work in your application, but I think there’s a good chance that it could, and for $14.99 it's worth a try.

I record Montage on two different computers. One computer is an M1 Mini and the other is an iMac. The Mini is not yet up to speed with 3rd party software, therefore sometimes I switch over to the iMac to record and mix. I have activated the Mac file sharing features and it works quite well.

I'm curious if the USB B port from the Montage can be split into two USB A cables?
If this would work it would allow me to not have to re-plug the keyboard USB every-time I change computers.

Thanks

Connecting a USB Slave (like Montage in this case) to more than one Master / Host (in that case your computer) is technically not foreseen and possible. You can reconnect the Montage to the currenty used computer - that is not a issue at all.