FLC OF A B727 OVERSHOT ASSIGNED DSCNT ALT RESULTING IN ATC INTERVENTION TO QUESTION THE ALT TO WHICH THEY WERE HEADED SINCE THEY HAD ALREADY PASSED ASSIGNED. ATC SUBSEQUENTLY CLRED THEM THE LOWER ALT TO WHICH THE FLC WERE HEADED AND THOUGHT THAT THEY WERE ASSIGNED.

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AS WE APCHED THE ARPT I HAD BEGUN TO TAKE CARE OF SOME OF THE USUAL DUTIES FOR THE FE SOME OF WHICH ARE ADJUST THE AIR-CONDITIONING SYS AND CALLING OPS WITH AN 'IN RANGE' CALL. WHEN I HAD FINISHED MY WORK AT THE PANEL I LOOKED FORWARD AND WE WERE DSNDING THROUGH APPROX 8500 FT MSL AND APCH RPTED TFC AT 7000 FT. ALL THREE OF US FOUND THE TFC BOTH VISUALLY AND ON THE TCASII. I THINK THE CAPT SAID THAT WE WERE GOING TO BE FAIRLY CLOSE BEHIND HIM (3- 5 NM). I TOOK THAT TO MEAN EXPECT APCH TO ASK US UP TO SLOW DOWN FOR SPACING. TO THIS POINT I HAD BEEN DISTRACTED BY MY RESPONSIBILITIES AT THE FE PANEL. APCH THEN CAME UP AND SAID ACR X ARE YOU DSNDING TO 7000 FT? THE QUESTION GOT MY ATTN (AS WELL AS THE CAPT AND FO). A QUICK SCAN SHOWED US DSNDING THROUGH APPROX 7600 FT MSL WITH 7000 FT IN THE ALT ALERT WINDOW. THE COCKPIT DISCUSSION WAS 'YES WE ARE'(?). I DON'T KNOW IF THE FO HAD TIME TO RESPOND TO THE CTLR BEFORE THE CTLR SAID YOU WERE ASSIGNED 8000 FT; YOUR TFC IS AT 7000 FT. HE FOLLOWED THIS WITH YOU CAN DSND TO 7000 FT NOW. WE DSNDED TO 7000 FT WITHOUT ALTERING COURSE OR AIRSPD AND THE REMAINDER OF THE APCH AND LNDG WERE UNEVENTFUL.