Jusy my 2 cents here, and rot is correct on the air intake...but just from what i see, you have 2 different reducers out of the exhaust or burner side, also you can tell that they are set at different heights, count your threads, also, bures and any obstructions will create a different flame, be sure to check that when fitting identical burners, make sure both are made from simular materials, also your nipple is screwed in further to your one side of your mixing chamber or reducer which ever your preference, you are creating less room for your venturi affect to take affect on 1 side then the other, those are just your starting points, other things to look at , with your set up is split setup, you have both burners running off of the same valve, what you need to look for is a difference between the 2, just like before check centers, and check threads, if your off even a 1/8 inch center, it will want to flow heavy to the shortest route, your best bet, run a single line to a duel setup, with 2 needle valves, this way you can control each burner, ill post a pic of my double burner setup for your reference, always look for obstructions, debure EVERYTHING, and always always double check measurements, your setup makes for alot of fun trying to get them to match perfect.
This is most ideal for double or triple burner set up