What is the ruling on the the prayer of a latecomer who joined the Imam during the last Tashahhud and completed his prayer with another latecomer?

If the latecomer (masbuq) only caught the Tashahhud and then prayed behind another latecomer who had caught one rak'ah, the prayer of the follower is valid, based on the opinion of those who permit a latecomer to follow another latecomer.