COMMUTER PLT REACTS TO TCASII RA WHILE ON APCH AND CLBS INTO DSNDING TFC BEHIND HIM RESULTING IN A PLTDEV.

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I ISSUED ACR X DSCNT TO 11000. I THEN ISSUED ACR Y DSCNT TO 16000. I OBSERVED ACR X LEAVING 13300 AT WHICH TIME I ISSUED ACR Y A DSCNT TO 12000 AND DIRECT HILLY. I OBSERVED ACR Y LEAVING 12700 AND OBSERVED ACR X LEAVING 11300. I INSTRUCTED ACR X EXPEDITE TO 11000 AND ISSUED VECTOR 010 DEG. ACR X THEN INFORMED ME HE WAS CLBING FOR TCASII. I THEN INSTRUCTED ACR X NOT TO CLB TFC ABOVE AND DSNDING. ACR X TURN R IMMEDIATELY HDG 090 DEG TFC AHEAD AND TO YOUR LEFT CLBING. I ASKED ACR X IF HE HAD ACR Y IN SIGHT. ACR X SAID YES; I THEN INSTRUCTED ACR X TO MAINTAIN VISUAL SEPARATION. ACR Y SAID HE HAD TFC IN SIGHT 'AND NONE TOO SOON.' SUPPLEMENTAL INFO FROM ACN 201229. DSNDING THROUGH APPROX 14-13500 FT; INITIATING OUR TURN; WE GOT A TCASII RA TO CLB APPROX 1500-2000 FPM. FO INITIATED CLB; I INSTRUCTED DENVER APCH WE WERE CLBING TO COMPLY WITH TCASII. DENVER APCH REPLIED; NEGATIVE; TFC ABOVE AND BEHIND YOU 400 FT.' FO INITIALLY REDUCED CLB. I INSTRUCTED HIM TO KEEP CLBING; TCASII GAVE US 'INCREASE CLB.' I INSTRUCTED DENVER APCH WE WERE CONTINUING CLB AND TO 'MOVE THE OTHER TFC.' HE GAVE CONFLICTING ACR Y A 090 DEG HDG. I LOOKED OUT MY WINDOW (L SIDE) AND SAW ACR Y UNDERNEATH US APPROX 3-400 FT INITIATING TURN TO 090. APPEARS CONFLICTING TFC CAME FROM OR R TO L UNDERNEATH US AND TURNED BACK UNDER OUR NOSE TO NEW HDG. I DO NOT REMEMBER CTLR ADVISING US OR CONFLICTING MLG OF EACH OTHER AT ANY TIME EXCEPT WHEN HE SAID NOT TO CLB BECAUSE TFC WAS 400 FT ABOVE US.