Normally you can do this but like Nolan said both units need the V2.01 firmware, it doesn't work on a 1.38.
Now to do this, you connect the midi out of the mp-1 you want to send from to the midi in of the mp-1 you want to recieve.
Then on the mp-1 you want to send from press STORE, it will light, then press the BANK button and while holding it press 6, the display will read "sending all"
No need to do anything on the recieving mp-1, an mp-1 is always ready to recieve sysex midi with a V2.01.
Also make sure both units are on the same midi channel (setting to "All" doesn't work I think, so choose a number). Also make sure the memory protect is "off" on the recieving unit. It usually is, but just in case you need to change it almost the same procedure, store, bank + 8 will turn memory protect on and off.