DH8 DSCNT THROUGH OCCUPIED ALT HAD LTSS FROM ANOTHER DH8. SYS ERROR.

Narrative

I WAS WORKING A SATELLITE SECTOR WHICH ALSO RUNS THE FINAL APCH FOR OUR SECONDARY RWY. THERE WERE 2 DH8'S BOTH ON THE SAME HDG; ONE AT 6000 FT THE OTHER AT 5000 FT. THE HIGHER ACFT WAS FASTER SO THE PLAN WAS TO LET HIM RUN BY THE LOWER THEN DSND FOR THE ARPT. I THOUGHT THAT I HAD GIVEN THE LOWER ACFT A SPD RESTR OF 190 KTS WHICH WOULD HAVE BEEN JUST ENOUGH TO DO WHAT I NEEDED. MY STRIP INDICATED THAT I DID ISSUE A SPD RESTR; HOWEVER; I LATER LEARNED THAT I HAD ISSUED THE RESTR TO ANOTHER ACFT WITH A SIMILAR SOUNDING CALL SIGN. THIS WAS A VERY BUSY SESSION AND MOST OF THE COMMUTERS WERE USING SIMILAR CALL SIGNS. THINKING THAT I WOULD HAVE ENOUGH ROOM I DSNDED THE HIGHER ACFT THROUGH THE ALT OF THE LOWER. THE CONFLICT ALERT ALARM SOUNDED SO I WENT BACK AND ISSUED DIVERGING HDGS TO BOTH ACFT. IN MY HASTE TO RESOLVE THIS SIT I CREATED ANOTHER BY TURNING THE LOWER ACFT TO CONFLICT WITH ANOTHER (PA28). THIS SIT WAS RESOLVED WITH THE DH8 MAKING AN IMMEDIATE CLB AND A TURN AWAY FROM THE PA28. LOOKING BACK I SHOULD HAVE HAD A HDOF MAN AS A SET OF EXTRA EYES. WE ALSO HAD JUST RECEIVED A NEW CONFLICT ALERT SYS THAT WAS ALERTING OF EVERYTHING THAT MOVED; SO THIS PROVED TO BE A HINDERANCE TO ME.