CROSSING DEPARTING AND ARRIVING MLG'S CLEARED TO SAME ALT.

Narrative

JUST PRIOR TO TKOF CLRNC WAS TOLD TO MAINTAIN 8000' ON DEP (AT LEAST THAT IS WHAT WE THINK WE HEARD AND WHAT WE SET IN THE ALT ALERT/ALT SET (A/P). AFTER TKOF WE TURNED TO OUR ASSIGNED HDG AND WERE TOLD TO LOOK FOR TFC AT 1 O'CLOCK. WE SPOTTED THE TFC AND WERE RELEASED TO DEP CTL. WE CHKED IN WITH DEP AND WERE TOLD WE HAD ADDITIONAL TFC AT 10-11 O'CLOCK; COMPANY ACFT; WHICH WE SPOTTED AND WHICH SPOTTED US. HE WAS XING LEFT TO RIGHT (WBOUND) ABOVE AND ABOUT A 1/2 MI AHEAD. WE WERE PASSING 7500 FOR 8000' AND I COMMENTED THAT HE MUST BE AT 9000'. SHORTLY THEREAFTER WE WERE CLRED TO CONTINUE OUR CLB TO 17000'. DURING THE CLB WE WERE CALLED BY ONE OF OUR COMPANY'S PLTS ON THE COMPANY RADIO. HE ASKED WHAT ALT WE HAD BEEN CLRED TO. WHEN TOLD THAT WE HAD BEEN CLRED TO 8000'; HE RESPONDED THAT HE TOO HAD BEEN CLRED TO 8000'. AS IT WAS HE SPOTTED US AND LEVELED AT 8700'--WE WERE PASSING 7500 FOR 8000'. UPON LNDG OUR FELLOW PLT CALLED APCH/DEP CTL. THEY SAID THEY WOULD REVIEW THE TAPES BUT NOT TO WORRY ABOUT IT. AS WE HAD NO TAPES TO REVIEW; I DON'T KNOW FOR SURE WHETHER WE WERE CORRECT OR IN ERROR ON OUR ALT CLRNC; WHETHER ATC WAS IN ERROR; OR WHETHER OUR COMPANY ACFT WAS IN ERROR. MY IMPRESSION IS THAT BOTH ACFT WERE CLRED TO 8000' AND THAT THERE WAS A MISCOORD BTWN APCH AND DEP CTL CAUSED POSSIBLY BY THE ALT AMENDMENT MADE AT THE END OF THE RWY JUST BEFORE TKOF. THIS MAY HAVE BEEN NECESSITATED BY THE TFC RPTED BY TWR AND SIGHTED BY US IMMEDIATELY AFTER TKOF (THE 1 O'CLOCK TFC). THERE DID NOT SEEM TO BE ANY NONPROFESSIONAL PERFORMANCE. IT APPEARS TO HAVE BEEN A ERROR BY 1 OF 3 PARTIES. WITH GOOD OUTSIDE VIGILANCE THE SITUATION WAS NEVER THREATENING; THOUGH IT MAY HAVE BEEN IF IN IMC.