PIC OF AN MLG SETS COCKPIT UP FOR A CAT III APCH. SELECTS #2 AUTOPLT PRIOR TO ARMING THE APCH MODE. AUTOPLTS DISCONNECT AND ACFT GOES THROUGH LOC; CREATING A POTENTIAL CONFLICT LTSS WITH ACFT Y.

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FOR CERTIFICATION PURPOSES IT WAS DECIDED THAT THE CAPT (PF) WOULD EXECUTE THE CAT III AUTOLAND TO RWY 36L AT CVG. CONDITIONS WERE DAYTIME AND VFR; APCH AGREED TO OUR REQUEST. AFTER BEING GIVEN A HEADING TO INTERCEPT THE FINAL APCH COURSE THE CAPT SELECTED THE SECOND AUTOPLT BEFORE ARMING THE 'APCH MODE.' THIS WAS INCORRECT AND CAUSED BOTH AUTOPLTS TO DISENGAGE. THIS THEN LED TO SOME CONFUSION IN THE COCKPIT AS WE ATTEMPTED TO CORRECT THE PROB. DURING THIS TIME WE WERE STILL ON OUR ASSIGNED INTERCEPT HEADING AND ULTIMATELY OVERSHOT THE FINAL APCH COURSE. THERE WAS PARALLEL TFC INBOUND TO RWY 36R WHICH WE CAME WITHIN 1 MI OF AND LED TO A TA FROM TCASII. AT THIS TIME WE ABANDONED THE AUTOLAND APCH; CORRECTED BACK TO THE FINAL APCH COURSE AND CONTINUED A MANUAL APCH. NO EVASIVE ACTION WAS NEEDED. THE DISENGAGEMENT OF THE BOTH AUTOPLTS WAS A DISTR FOR BOTH OF US WHICH LED TO REDUCED SITUATIONAL AWARENESS. SUPPLEMENTAL INFO FROM ACN 362570: I DECIDED TO FLY AN AUTOLAND APCH IN ORDER TO FINISH MY CERTIFICATION FOR CAT III OPS.