ACR X TCASII RA ON FINAL APCH HAD NMAC WITH ATX Y. EVASIVE ACTION TAKEN. SEE AND AVOID CONCEPT.

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ACR X WAS ADVISED CONTACT TWR ON 126.55 AND MAINTAIN SPD NECESSARY FOR SEPARATION FROM LTT AHEAD. VISUAL APCH TO RWY 17L. AT JIFFY 7.2 DME I SAW A TARGET ON TCASII ENTERING THE 2 MI SEGMENT AT 500 FT ABOVE ON OUR L. I CALLED IT TO CAPT'S ATTN. HE STATED THAT HE SAW THE ACFT TURNING TO FINAL ON OUR L. THE TARGET WAS AMBER IN COLOR AND CLOSED FROM OUR L QUARTER AND VERTICALLY. I WAS ACCELERATING FORWARD AND VERTICALLY WHEN THE TARGET TURNED RED AND TCASII INDICATED 100 FT DIRECTLY ABOVE. THE TCASII COMMANDED 'DSND;' WHICH I WAS ALREADY DOING. WHEN THE TCASII ANNOUNCED CLR OF CONFLICT; I RECEIVED A GS WARNING AND I WAS CLOSING ON LTT. CAPT ASKED THE TWR ABOUT TFC BEHIND US. THE TWR ADVISED THAT THE TFC WAS FOLLOWING US VISUALLY TO LAND ON 13L (AT THIS POINT BELIEVE THAT THE TFC (ATX Y) WAS INCORRECTLY FOLLOWING THE LTT AHEAD OF US). THE TFC AGAIN BECAME A CONFLICT AS IT APPEARED WITHIN THE CIRCLE AND DIRECTLY ABOVE. IT MOVED TO OUR L FRONT AND WITHIN 100 FT. WHEN THE TCASII AGAIN COMMANDED 'DSND;' I WAS AGAIN INCREASING SPD AND VERT DSCNT. WE WERE CLOSING ON THE LTT AND AGAIN RECEIVED A GS WARNING. WE RECEIVED A CLR OF CONFLICT ANNOUNCEMENT. CAPT AGAIN ASKED ABOUT THE TFC BEHIND US. ANOTHER CTLR CAME ON (I BELIEVE TO BE THE FINAL CTLR) AND SOUNDED VERY IRRITATED WHEN HE SAID 'WE TOLD YOU THAT THE TFC WAS FOLLOWING YOU AND WE HAVE BOTH OF YOU IN SIGHT.' WE LANDED AND EXITED AT THE HIGHSPD TO INTXN 27. WHEN WE TURNED N ON LIMA; WE SAW THAT THE ATX Y WAS TAXIING N ON RWY 13L.