ZTL CTLR EXPERIENCES NEAR LOSS OF SEPARATION BECAUSE OF SAME ACFT TYPE BUT DIFFERENT SPDS.

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ACFT X PA32/G T130 6000 FT JQF-AVL. ACFT Y PA32/G T135 6000 FT JQF-AVL. SAME TYPE ACFT; RIGHT? NOT! THE BACK ONE IS A LANCE. THE FRONT ONE IS A CHEROKEE SIX. THE COMPUTER ESTIMATED A 4 KT DIFFERENCE IN SPD. I TOOK THE HDOFS FROM CLT APCH. BOTH ACFT LEVEL. BUSY TFC. I LOOKED AT THE ACFT AGAIN AS THEY ENTERED MY AIRSPACE AND THEY APPEARED MUCH CLOSER. I ASKED THE FRONT ONE HIS SPD; 110 KTS. THE BACK ONE (ACFT Y) WAS 135 KTS. I ISSUED ACFT Y A SPD REDUCTION AND A 45 DEG TURN. CLOSEST APCH WAS APPROX 5.2 MI. I PROBABLY DON'T HAVE TO TELL YOU HOW DISTRACTING A SIT LIKE THIS IS. BUT I MISSED CALLING A VFR TO OTHER TFC I WAS WORKING DURING THIS. MY D-SIDE WAS PREOCCUPIED TRYING TO SHOW ANOTHER CTLR HOW TO OPERATE SOME NEW TECHNOLOGY. THAT'S HOW THE BIG ONE IS GOING TO HAPPEN. EACH ONE OF THESE SEEMINGLY INCONSEQUENTIAL 'STRAWS' IS GOING TO PILE UP AND EVENTUALLY BREAK THE 'CAMEL'S' BACK. IT'S A GOOD THING ACFT Y WASN'T A SARATOGA (YET ANOTHER PA32) OR IT WOULD HAVE BEEN A DEAL. THEN THEY COULD HAVE DECERTIFIED ME AND THE D-SIDE AND THE AREA COULD HAVE WORKED EVEN MORE SHORT STAFFED THAN WE ALREADY WERE.