The only ones I know of are the Roland A-80 (somewhat rare) and Kurzweil MIDIBoard (very rare), both circa 1988.
The Gem S2 and S3 (as mentioned by TheOtherHobbes) from around 1992 - these do indeed have poly aftertouch, but neither of them are weighted.
Ensoniq was the company who most consistently used poly aftertouch in their keyboards during this era, but AFAIK only ever on the synth-weight keys. For their models that had weighted keyboards, they would use a keybed made by Fatar which only provided regular aftertouch, not poly.
The Gem S2 and S3 (as mentioned by TheOtherHobbes) from around 1992 - these do indeed have poly aftertouch, but neither of them are weighted.
Ensoniq was the company who most consistently used poly aftertouch in their keyboards during this era, but AFAIK only ever on the synth-weight keys. For their models that had weighted keyboards, they would use a keybed made by Fatar which only provided regular aftertouch, not poly.