The pilot of the Legend Cub reported that during the landing roll on the runway of a non-towered airport, an airplane struck his airplane from behind. The Cub sustained substantial damage to the empennage. The pilot of the Ercoupe reported that he communicated his intention to land on the runway behind the Cub over the common traffic advisory frequency (CTAF) while on a final approach. The pilot determined to proceed with his approach, assuming that the Cub was clear of the runway. The airplane bounced during the landing, and the pilot decided to forgo a go-around and instead continue the touchdown. During the landing roll, shortly after looking up from the instrument console, the pilot saw the Cub taxiing on the runway. Immediately, the Ercoupe pilot applied brakes and the Ercoupe’s left wing tip stuck the Cub’s empennage. Subsequently, the Ercoupe sustained substantial damage to the left-wing spar and left aileron.