It would be quite funny.
I guess there can be an online server with a version of Mugen installed and where more than one person is able to connect using TeamViewer or some similar. The players should enter the configuration menu in order to set their keyboards (maybe both keyboards are recognized as a single one for the server and different keys must be set for every player).
I don't know. It would be interesting to try.
For sure, that would be useful as platform to atract new people to Mugen.