Bonanza 35
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 7.1
Confusion; Situational Awareness; Troubleshooting
ATC Issue All Types; Airspace Violation All Types
ATC Equipment / Nav Facility / Buildings
I was working DR1 and accepted a handoff from DR2 on a tag that read Aircraft X. The pilot asked for a Bravo clearance and climb which I issued. When I saw that the aircraft did not appear to be climbing; I began making inquiries. The altitude indicated 061 and an approximate 240 heading; not the climb to 085 on a 170 heading I'd issued. I attempted to turn further right to a 150 with no visible change. I asked for his altitude; thirty degree turns and finally to IDENT since I'd seen no change. In between some of this questioning; BJC called to say they tagged up a VFR as a Bravo violator 'BVIO' and wanted me to track him and have him call. When I asked Aircraft X to IDENT; I observed the BVIO IDENT. I asked for position and correlated it to that spot; 20 miles south of the AC DR2 identified as Aircraft X.After watching the replay we discovered that a code [XXYY] departed GXY. When DR2 got the call from Aircraft X and typed it in; the generated code was also [XXYY]. The system tagged the aircraft off GXY instead of the actual Aircraft X who departed BDU almost 35 miles apart. When DR2 called the position correctly; the pilot did not catch that it was incorrect. The real Aircraft X flew through BJC's airspace; through their traffic pattern; and I didn't make the connection until I saw the BVIO with an IDENT. I had to watch the replay to figure out how all of that happened.There were two aircraft squawking [XXYY] and the system didn't show any indication of it. I'd like to see that the system either not allow that to happen or at least have some sort of notification that it's happened.
Denver TRACON Controller reported the ATC Computer allowed two aircraft to be tagged up on the same code; which led to confusion and airspace violations.