A Twinset can be put together at very low cost with any used keyboard.
Important it has Midi.
My Twinset is TOP T5-76-LOWER Np30.
The NP30 Drives T5 ACC's & Styles over it's full length.
T5 now has full keys to split into different voice zone.

With my LOWER controlling all sounds on the UPPER it's volume is muted.
The 2 boards need to be as close as possible together so LOWER controls are not needed.

https://app.box.com/s/lymi6906rhn9pnvvrlkpi1213ybd5kwr