Never saw it on my son's team in HS....... our pitcher was normally one of our better hitters so he was n the lineup.
My son has been in this situation a couple times this year in college. He started the game at DH.....then came in in relief on the mound....then remained in the game as the DH. Our team's radio guy isn't really up on rules....boy was he confused when my son was still batting after he had finished on the mound. Another game, the starting P was also the DH....son came in to throw, but went took our original 1B's position in the order. Original P stayed as the DH but played 1B after he was done on the mound. Man, the poor radio guy had no idea what to say when both of the pitchers were still batting the next inning.