Son is 18 and lives with me. he filed his taxes for p/t job and checked someone can claim you as a depend. now our return was rejected because it says he claimed himself.

He made a $1030 for the year. His return has box checked saying someone can claim you as a dependent. I claimed him as a dependent on our return and received a $500 dependent credit. We tried to e file and our return was rejected because it says he was claimed as a dependent on his own return. On box 8 of his return has a amount of $1327 entered. He used TurboTax also. Do we need to leave our return as it is and mail it in? Thank You