Option to allow only one instance of the player running

[CosmicHeron]

A minor feature request to add in an option to allow only one instance of the player running. If dmidiplayer is playing a file and outputting it to MIDI port 1, for instance, opening another midi file will, instead of replacing the currently playing file, start up another instance of the player and start outputting to the same port. Can the player (or ALSA) detect that a MIDI port is currently being used to prevent midis from trampling over each other?