FLT CREW WAS ISSUED DSCNT CLRNC FOR THE APCH BY BRAZILIAN ATC. INTERMEDIATE LEVELOFF WAS THEN GIVEN TO AVOID DSNDING THROUGH ANOTHER ACFT'S ALT.

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I HAVE HAD TWO EVENTS ON TWO SEPARATE FLTS WITH THE SAME SEPARATION ISSUE LNDG IN BRAZIL IN THE LAST 35 DAYS. THE FIRST EVENT OCCURRED ON A FLT TO SBGL. I WAS JUST RETURNING TO THE COCKPIT FROM MY BREAK (FO) AND WE HAD BEEN CLRED TO DSND TO FL120 FROM OUR CRUISE ALT VIA THE SULI ARR. THE CAPT INITIATED THE DSCNT; AND THE CTLR CAME BACK AND TOLD US WHILE DSNDING THROUGH FL350 TO 'STOP THE DSCNT AT FL350.' WE WERE DSNDING AT APPROX 2000 PLUS FT A MINUTE (KEPT UP AND WERE TRYING TO GET BACK ON PROFILE) AND DSNDED TO APPROX 34600 FT AND THEN CLBED BACK TO FL350. DURING THE PROCESS THE CTLR MADE ANOTHER CALL THAT 'TFC AT 6 O'CLOCK 1 MILE FL350.' THE CAPT SAW THE TFC ON THE TCAS AT ABOUT 1 MILE; I DID NOT. NO TA OR RA. THIS FLT HAD ALMOST THE EXACT SAME SIT. RETURNING FROM BREAK AND STILL AT CRUISE; CLRED TO FL150 VIA THE TUC 9 ARR. WHILE DSNDING THROUGH FL270 THE CTLR TOLD US TO STOP THE DSCNT AT FL250; WHICH WE DID WITH NO PROB. ALTHOUGH NO TFC WARNING WAS GIVEN; AGAIN WE BOTH SAW TFC AT 6 O'CLOCK AND ABOUT A MILE AT FL240 ON TCAS. NO TA OR RA.