If one charger is charging one or more cells a little more than the other (your 4.23 reading) That could explaine the difference in mah. Unless the batteries get unreasonably warm during a charge I wouldn't worry about it. It's easy to over analyze this stuff at the price we gotta pay.
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It's "Dr. _paralyzed_" actually. Not like with a PhD, but Doctor like in Dr. Pepper.
I have ,and use daily the same charger that you use.the minimal voltage variation you are seeing imho will not effect anything.Like i previously stated ..03 volt is not worth worring about.If you were talking .3 volts there may be a problem with your charger and or battery.