A PA31 PILOT IN THE PDK TFC PATTERN WAS CLEARED FOR VISUAL TO RWY 2L BUT TRACON PREVIOUSLY CLRED HIM FOR A RWY 20R VISUAL CAUSING CONFUSION.

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I WAS CLRED FOR AN APCH (VISUAL) TO RWY 20R AT PDK BY APCH CTL AND THEN XFERRED TO PDK TWR. THERE WAS A DELAY BEFORE I COULD TALK TO PDK TWR AS THE CTLR WAS VERY BUSY WITH OTHER ACFT AND I COULD NOT BREAK IN. I COULD SEE NUMEROUS ACFT IN THE IMMEDIATE AREA ON MY TCAS AND HESITATED TO TURN TOWARD THE APCH END OF RWY 20R UNTIL CONTACTING TWR. I HAD INTENDED TO TURN R FOR A L BASE TO FINAL FOR RWY 20R. HOWEVER; BY THE TIME I GOT TO THE TWR; I NEEDED TO MAKE A R TURN FOR RWY 20R BASE-TO-FINAL. ONCE I CONTACTED THE TWR THERE WAS SOME CONFUSING CONVERSATION REGARDING MAKING A L OR R TURN TO FINAL. IT DID NOT OCCUR TO ME UNTIL AFTER SEVERAL TURNS THAT THE TWR CTLR WAS CLRING ME TO LAND ON RWY 2L AND APCH CTLR HAD CLRED ME FOR RWY 20R. I ULTIMATELY DID DO A VISUAL APCH AND LNDG ON RWY 2L. I WAS THINKING RWY 20R ALL ALONG AND DID NOT PICK UP THAT THE TWR CTLR WAS CLRING ME FOR RWY '2L.' I AM NOT SURE WHERE IN THE CLRNC THAT THIS CHANGE OCCURRED AS I DID NOT REALIZE THE MISUNDERSTANDING UNTIL WE HAD MADE SEVERAL TURNS. THE CONFUSION CAME WITH DISTINGUISHING RWY 20R FROM RWY 2L.