Thanks for all the feedback! Based on my original criterial that the pair of spinners must be in the middle of the playfield, I've moved a few of the games mentioned to an "Honorable Mention" category. Below are the 8 games (13 counting variations) ordered by release date that meet the stated criteria so far:
1972: GOTTLIEB King Kool (2p) / King Rock (4p)
1975: CHICAGO COIN Red Baron (2p) / Blue Max (4p)
1975: BALLY Bow & Arrow
1976: PLAYMATIC Conquest 200 (1p) / New World (4p)
1977: GOTTLIEB Soccer (2p)/ Supper Soccer (4p)
1977: SEGASA Prospector
1977: STERN Disco
1979: BALLY Harlem Globetrotter World Tour (aka Basket World Trotter in Italy)
It's interesting that all of these games came out in the 70s, are mostly EMs, and peaked in 1977 with three games. Also, 5 different manufacturers made at least one game with this feature, but no manufacturer made more than two. (I'm counting Chicago Coin and Stern as the same manufacturer since CC became SEI when Sam Stern bought them.)
Also interesting is that the last game released meeting the criteria is also one of the best selling of all time, with Harlem Globetrotter shipping nearly 15,000 units! We don't have numbers on all of these, but Disco may be the worst performing of these games with just 812 made.
Here are the honorable mentions that didn't make the cut based on my "middle of the playfield" criteria technicality since the spinners are closer to the edge than the middle or offset to one side:
1976: WILLIAMS Blue Chip (Close, but spinners appear to be nearer to the outside edge of the playfield than the middle)
1977: SEGASA Mars Trek (Offset to right)
1980: ZACCARIA Star God (Offset to right and slanted)
1988: WILLIAMS Swords of Fury (Offset to left and slanted)
If anyone thinks of any more games (especially anything that predates King Kool) then post it here and I'll update my list.
Twin Middle Spinner Games by Year (resized).png