MIDI keyboard mixer

I alternate between several keyboards when I play (ala Rick Wakeman), and even use old Moog Taurus pedals or Roland MIDI pedals. Of course, the VoiceLive 2 only has one MIDI input. Is there such a thing somewhere as a 4-6 input mixer that has MIDI inputs, and at least one MIDI output, so I can run all my keyboards into the VoiceLive 2 (so that whichever one I play, I can get vocal harmony)? Or, is there another way to solve this problem?
Thanks