Amazon.com: MIDI Splitter Cable, MIDI 5 Pin DIN Plug Male to 2 DIN Female SmartPhone AUX Headphone Stereo Jack Adapter Y Input Cable for MIDI keyboard, electric piano, synthesizer, MIDI guitar :
MeeBlip cubit: 4-port MIDI splitter | meeblip
20 way MIDI Thru Splitter unit for synthesizers from JACK on Tindie
Banana Split - 6 Way Midi Splitter/Thru Box from Sixty Four Pixels on Tindie
Sixty Four Pixels Banana Split 6 Way MIDI Splitter Thru Box - | Reverb
MIDI Splitter - splits MIDI signal from one input to four outputs