A DH8-Q400 EMER CHECKLIST CONTAINS 2 'LANDING GEAR DOOR MALFUNCTION' PROCEDURES. THE INCORRECT CHECKLIST WAS RUN BY THIS CREW.

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ON TKOF OUT OF ZZZ1 UPON GEAR RETRACTION; FO NOTICED BOTH MAIN LNDG GEAR DOOR AMBER LIGHTS WERE ILLUMINATED. THE CAPT CALLED FOR THE 'LNDG GEAR DOOR MALFUNCTION' CHKLIST. THE FO WENT TO THE EMER CHKLIST INDEX AND PROCEEDED TO RUN THE 'LNDG GEAR DOOR MALFUNCTION CHKLIST.' UPON COMPLETION OF THE CHKLIST THE MALFUNCTION WAS RESOLVED WITH NO FURTHER ACTION REQUIRED AS PER CHKLIST. ON TKOF OUT OF ZZZ2 UPON GEAR RETRACTION; THE CAPT NOTICED THAT THE L MAIN GEAR AMBER LIGHT REMAINED ILLUMINATED. THE CHKLIST WAS RUN AGAIN. ONCE AGAIN RESOLVING THE PROB AT THAT TIME. WE ADVISED MAINT CTL THAT MAINT WAS REQUIRED UPON REACHING ZZZ3. AFTER LNDG IN ZZZ3 WE REVIEWED THE SITUATION AND IT WAS DETERMINED THAT THERE ARE IN FACT 2 CHKLISTS BOTH TITLED 'LNDG GEAR DOOR MALFUNCTION CHKLIST.' ONE IN WHITE AND ONE IN BLUE PRINT. WE HAD IN FACT RUN THE ONE IN WHITE AS PER THE INDEX. IN A PHONE CONVERSATION WITH THE DUTY OFFICER AT THE TIME; WE DISCUSSED THE SITUATION. WE BELIEVE THAT THE EVENT OCCURRED AS A RESULT OF THE FOLLOWING; A VERY BUSY PHASE OF FLT LEVELING OFF; CHANGING CTLRS AND HDG; WITH A RELATIVELY NEW FO; FIRST LEG OF DAY. THESE WERE ALL CONTRIBUTING FACTORS TO MISIDENTING 1 OF 2 CHKLISTS WITH THE EXACT SAME TITLE. I BELIEVE IT WOULD BE VERY HELPFUL AND MUCH LESS CONFUSING IF IN THE EMER CHKLIST THERE WAS ONLY 1 CHKLIST. BY THAT WE MEAN IF A NEW CHKLIST OR PROC IS ADDED; THE OLD ONE NEEDS TO BE REMOVED TO AVOID THE POSSIBILITY OF RUNNING THE WRONG PROC.