B737-300 CAPTAIN REPORTS BEING DISPATCHED WITH FORWARD PA INOPERATIVE AND THE AFT PA WORKING. FLIGHT ATTENDANTS INFORM CAPTAIN AT TRIP END IT IS THE OTHER WAY AROUND. MECHANIC HAD SWAPPED MICROPHONES DURING TROUBLE SHOOTING WITHOUT MAKING LOG ENTRY. MAINTENANCE RELEASE WAS NOT CORRECT.

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ILLEGAL MAINT DISPATCH. WE PICKED UP ACFT X FOR FLT ZZZ. WE SUBSEQUENTLY FLEW THE SAME ACFT FROM ZZZ TO ZZZ1. ACCORDING TO THE FLT PAPERWORK; MAINT HISTORY AND THEN CURRENT MAINT RELEASE; THE FORWARD PA WAS INOP; BUT THE AFT PA WAS OPERATIONAL. I BRIEFED THE FLT ATTENDANTS OF THE SITUATION AND THEY AGREED THAT THE ACFT WAS SAFE IN THIS CONFIGN; AND THEY WERE FAMILIAR WITH THEIR RESPONSIBILITIES RELATED TO THIS DEFERRAL. UPON ARR IN ZZZ; THE FLT ATTENDANTS WERE GETTING OFF OF THE ACFT AND RPTED TO ME THAT THE FORWARD PA WORKED FINE -- IT WAS THE AFT PA THAT WAS INOP. I RPTED THE SAME TO THE MECH WHO CAME TO THE PLANE TO ADDRESS OTHER WRITE-UPS. THE MECH INFORMED ME THAT IN ZZZ2 THE MECH THERE HAD SWAPPED PA MIKES FROM THE FORWARD AND AFT POSITIONS; MAKING THE AFT PA INOP WHILE MAKING THE FORWARD PA USABLE. THE MECH SHOWED ME THE INFO ITEM THAT THE MECH HAD ENTERED IN ZZZ2. I THEN SPOKE WITH THE MAINT CTL MGR ON DUTY. HE RESEARCHED THE ISSUE AND CONFIRMED EXACTLY WHAT THE ZZZ GATE MECH TOLD ME; AND THAT THE MECH IN ZZZ2 SHOULD NOT HAVE MADE AN INFO ENTRY; BUT SOME OTHER TYPE OF ENTRY. THIS WOULD HAVE AFFECTED THE EXISTING DEFERRED ITEM AND FORCED HIM TO EDIT THE DEFERRED ITEM TO SHOW THAT THE AFT PA WAS NOW INOP AND THE FORWARD ONE WORKED. I ASKED THE MAINT CTL CTLR TO PLEASE GET HOLD OF THIS ZZZ2 MECH FOR PURPOSES OF FILING A RPT; AND HE SAID HE WOULD. SO FOR 2 LEGS; THE MAINT RELEASE WAS INCORRECT IN THAT THE DEFERRED ITEM WAS NOT UPDATED AND THE LOCATION OF THE INOP COMPONENT WAS WRONG; THOUGH THE MAINT RELEASE VERIFICATION PROCESS SHOWED THAT WE HAD THE CORRECT AND LEGAL MAINT RELEASE.