ACR LTT PIC FOLLOWS WRONG ACFT FOR VISUAL APCH AFTER TA GIVEN.

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WHILE BEING VECTORED FOR A VISUAL APCH TO RWY 18R AT CVG; TFC TO FOLLOW WAS POINTED OUT AT 1 O'CLOCK AND WE WERE TOLD TO FOLLOW HIM. WE SAW THE TFC A FEW MOMENTS EARLIER AND WERE CLRED FOR THE VISUAL APCH WHEN WE ACKNOWLEDGED THE TFC WAS IN SIGHT. AT THAT TIME WE DSNDED OUT OF 7000 FT FOR THE APCH AND LNDG. OUR BASE TURN WAS MADE AS THE OTHER ACFT (A COMPANY LTT) WAS ABEAM OUR WING. HIS ALT (AT LEAST WHEN WE FIRST SAW HIM) WAS ABOUT 4500 FT. ON BASE LEG; THE CTLR ADVISED US THAT WE SHOULD EXTEND OUR BASE LEG BECAUSE CTLR THOUGHT THE SPACING WAS CLOSING UP (CTRL ALSO ADVISED THAT WE SHOULDN'T EXTEND THE BASE TOO LONG BECAUSE SIMULTANEOUS APCHS WERE BEING MADE TO 18L). WE WEREN'T SURE WHY CTLR WAS SO CONCERNED ABOUT SPACING; BECAUSE WE CLRLY HAD THE ACFT IN FRONT OF US IN SIGHT. WE WERE IN TRAIL BY APPROX 5 MI. THE CTLR THEN ADVISED US THAT CTLR MAY HAVE TO BREAK US OFF THE APCH AND RESEQUENCE US. CTLR THEN SAID WE WERE DIRECTLY OVER THE ACFT WE WERE TO FOLLOW. THIS GOT OUR COMPLETE ATTN; TO SAY THE LEAST. THE ACFT THEN EMERGED FROM UNDERNEATH US AND MOVED TO OUR 2 O'CLOCK POS. HIS ALT WAS APPROX 2000 FT (OR MORE) BENEATH US. WE DROPPED FLAPS AND GEAR AND SLOWED TO FINAL APCH SPD TO INCREASE SPACING. WE LANDED ABOUT 3 MI IN TRAIL OF THE TFC. NO EVASIVE MANEUVERS WERE NEEDED. APPARENTLY; WE HAD THE WRONG TFC IN SIGHT FROM THE START. OUR EXCESSIVE DOWNWIND ALT (THANKS TO ATC) OF 7000 FT PRECLUDED OUR SEEING THE CORRECT TFC (WHICH WAS DOWN LOW AT 2500 FT APPROX). THE FACT THAT WE SAW TFC AT PRECISELY THE POS CALLED BY THE CTLR ONLY CONTRIBUTED TO THE MIX UP. AS PLTS; WE SHOULD ALWAYS ASK FOR ALT INFO ON TFC WE ARE TOLD TO FOLLOW. ALSO; JUST BECAUSE EVERYTHING 'LOOKS' RIGHT; THE TFC YOU SEE MAY NOT BE THE CORRECT ONE.