Ulamaa ID 04
Al-jawab billahi at-taufeeq (the answer with Allah's guidance)
If you read Tashahhud again or continue reading Durood in the second Tashahhud of a third or fourth Rakah Salah, it will be necessary to do the Sajdah Sahwa. (Ahsanul Fataawa Vol. 4 Pg. 29)
And Only Allah Ta'ala Knows Best.