Amazon.com: GLHONG 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 :
G-LAB MIDI 3x Splitter M3S Conmutador MIDI
MIDI Splitter
Split MIDI, without latency, for under $40: meet MeeBlip cubit - CDM Create Digital Music
MeeBlip cubit duo: USB MIDI interface and MIDI thru | MeeBlip Europe [Create Digital Media GmbH]