There were several two-seat adaptations of the Kingcobra, which paralleled the development of the TP-39 two-seat Airacobra.
The TP-63A-10 (Model 38) was a proposed two-seat Kingcobra variant. It was basically inspired by the two-seat TP-39 Airacobra. A new cockpit grafted onto the nose ahead of the existing cockpit of the P-63, with a leftward-opening canopy installed. All armament was removed, and a ventral fin was added. The basic idea was for the company to build conversion kits for existing P-63A-10 aircraft. However, none were actually built at the factory, although at least three were completed in the Soviet Union (42-69304, 42-70503, and 43-11334).
An entirely different two-seater was produced by the Bell company for internal use. Two P-63E-1s were modified by Bell with a separate observer seat in the rear fuselage, located behind the engine and mounted under a separate canopy. A probe was mounted which extended through the spinner, and to make space for the observer the radio equipment had to be moved forward into the armament bay. The aircraft carried the civilian registrations NX41963 and NX41964.