Dear Br. H. As-salaamu alaykum. Yes, one Azan for the Khutbah of Jumaa is considered sufficient and the prayer and Khutbah are considered valid. However, doing two Azans (instead of one) is a Sunnah and is recommended. Thank you for asking and God knows best.
(Source: IslamiCity) Classified in Azan for Friday Khutbah >