If it is on a parallel charge board all the batteries will be exactly the same since they are actually shorted together and the cells will "balance" with their partner cells in the other batteries, that's not the weird part, if your charger was mis-calibrated, which iSDT's often are, then all charging should have this mismatch. Do 3s and higher batteries charge ok? And do they charge to 4.2 roughly? It is possible to calibrate iSDT chargers yourself, but you kind of need a calibrated voltage meter to do it. Don't trust the LED segment on a parallel board, or even a battery checker as they can be way off, check with a voltmeter if you have one to see if they are really that far off.