Commercial Fixed Wing
Air Traffic Control Fully Certified
Air Traffic Control Radar 17
Confusion; Communication Breakdown
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Air Traffic Control Provided Assistance
Procedure
I was working the A-side position when I was asked to assist the Radar Controller at Sector XX with a duplicate callsign issue. ZZZ Sector XX was attempting to manually hand off an air carrier; but there was already an aircraft with that callsign in YYY airspace. Both aircraft were on different flight plans and would have been approximately 50 miles apart in YYY airspace. We coordinated a callsign change for the aircraft entering YYY airspace to an air carrier and entered a flight plan for them.Ensure the airlines file different callsigns for each flight.
ATC discovered duplicate call signs and changed the call sign of one of the two aircraft involved.