Doubleshot PBTs. Sadly nonexistent.
Dye-sublimated Cherry Corp PBT keys would be the closest to double-shot molded PBT keys.
Unlike modern PBT keys, they are just as thick-walled as the vintage double-shot ABS keys, and dye-sublimation is a more durable method than laser engraving. There are also some laser-engraved Cherry Corp PBT keys that are just as thick.
Dye-sublimated Cherry Corp PBT keys are some of the most high-priced key caps there are among collectors.