That is a thru box. The signal from the input goes to all of the four outputs unchanged.
There's nothing stopping you from sending MIDI on 4 (or more) different channels but it will go to all the connected devices and you'll have to set each of them up to respond only to their own particular channel(s). That's how MIDI works.
The reason you may need to use that is because daisy chaining midi devices usually screws up at more than two devices. But it depends, usually, on the devices used.