POSSIBLE TRANSPOSITION OF CALL SIGNS CAUSES HOLDING INCIDENT.

Narrative

ENRTE FROM PHL TO DFW; ON THE BLUE RIDGE 6 ARR INTO DFW; WE WERE CLRED TO HOLD AT CONNY INTXN AS PUBLISHED AT FL280. APCHING CONNY; WE WERE CLRED BY THE CTLR TO DSND TO FL250 AND MAINTAIN THAT IN THE HOLDING PATTERN. WE REPEATED BACK FL250 TO THE CTLR; AND SHE SAID; NO; THAT WE WERE CLRED DOWN TO FL240. WHEN WE GOT TO FL240; WE NOTICED ANOTHER ACFT (A B-727; I BELIEVE) IN THE SAME HOLDING PATTERN. HE WAS AHEAD OF US AT CONNY INTXN MAKING HIS R HAND TURN AND HE WAS AT THE SAME ALT. AS WE NOTICED THIS AND WERE ABOUT TO CALL CTR; THE CTR CTLR ASKED OUR ALT; WE SAID FL240. SHE SAID TO CLB BACK UP TO FL250 AND TOLD US OF THE ACFT AT THE SAME ALT. WE TOLD HER THAT; WE HAD DSNDED TO FL240 INITIALLY BECAUSE SHE TOLD US TO AND THAT WE HAD READ BACK FL240 AND NOTHING WAS SAID TO US WHEN WE READ IT BACK. WE WERE AT THE SAME ALT; BUT BASICALLY FOLLOWING THE OTHER ACFT IN THE HOLDING PATTERN. FORTUNATELY IT WAS VMC; NOT IMC; THOUGH WE DID NOT KNOW IF OUR SPD WAS GREATER THAN THE OTHER ACFT. I BELIEVE THAT SINCE BOTH ACFT WERE COMPANY AIRLINES; THE CTLR CONFUSED THE CALL SIGNS AND THE ALT. MAYBE WE WERE ORIGINALLY SUPPOSED TO GO FL250 (AS SHE ORIGINALLY SAID) AND THE OTHER ACFT WAS CLRED TO FL240 ALMOST SIMULTANEOUSLY IN THE STACK.