MLG SEES LGT ON VISUAL APCH IN CLOSE PROX THEN LATER HEARS SMA GIVEN GO AROUND AND SEES THAT ACFT IN CLOSE PROX. REPORTER CITES POOR ATC TECHNIQUE.

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WE HAD BEEN CLRED TO 3000' AND INTERCEPT THE LOC TO 24L. BECAUSE OF AN EARLIER RESTRICTION WE WERE ABOUT 1000' HIGH ON INTERCEPT. AS WE INTERCEPTED IN A LEFT TURN WE SAW AN LGT Y IN A RIGHT TURN IN FRONT OF US COMING FROM OUR RIGHT TO LEFT; LESS THAN 1/2 MI AND 1000' BELOW. OUR EXCESS SPD CLOSED THIS GAP SOMEWHAT. WHEN WE ASKED ABOUT IT WE WERE TOLD FOR THE FIRST TIME IT WAS ON A VISUAL APCH TO THE PARALLEL RWY. WE WERE APPROX 5-7 MI OUT AND COULD ONLY SEE ONE SET OF APCH LIGHTS (OTHER SET NOTAMED OUT). WE WERE TURNED OVER TO TWR AND RECONFIGURED FOR A HIGH DRAG DSCNT AND CONTINUED APCH FOR RWY 24L. BTWN 2-3 MI OUT WE CONTACTED TWR AND WERE CLRED TO LAND ON RWY 24L. BTWN 1 1/2-2 MI AT ABOUT 900'; TWR XMITTED A GARBLED COMMAND TO EXECUTE A MISSED APCH. WE IMMEDIATELY QUESTIONED THE CALL AND UNDERSTOOD THE NEXT CALL FOR AN SMA Z TO GO AROUND AND GAVE A HDG. WE WERE AT APPROX 500' AND 1 MI AND WERE RECLRED TO LAND. WE SPOTTED THE SMA Z OVER THE APCH LIGHTS CLBING RIGHT TO LEFT HDG S. WE PASSED BEHIND THIS ACFT AT ABOUT 200' ALT WITH LESS THAN 500' SEP. NORMAL LNDG. WHEN ASKED GND CTLR SAID HE HAD BEEN CLRED TO LAND; BUT HAD REALLY SLOWED DOWN. IN BOTH CASES; WE HAD NOT BEEN ADVISED OF THE PRESENCE OF THE OTHER ACFT UNTIL THE INCIDENT. BOTH ACFT WERE UNDER POSITIVE CTL. ONLY BECAUSE WE WERE OUT OF POS BECAUSE OF AN EARLIER RESTRICTION DID A SEVERE INCIDENT WITH THE LGT Y NOT OCCUR. WE NEVER SAW THE SMA Z UNTIL HE STARTED HIS GO AROUND.