You will have to be a little more specific to your problem... So you have new batteries and they're reading at different voltages?
How are you reading these voltages? Multi meter, Mod, Charger?
Have you charged the batteries yet? If you just received them, they will be in a "Storage Charge" which is about 40-60% of a full charge. Not all batteries in storage will read the same on a volt meter, they need to be "topped up" or placed on a charge first.
I believe you're saying you have a nitcore charger, most of them are alright quality. What exact model is it?
I would charge all batteries fully, then measure voltage. They should all be 4.20 Volts fresh off a charger. Any lower and your charger is not fully charging which poses no safety concern, just less battery life. Any higher and the charger is over charging, which can be very dangerous. Any voltage over 4.25 is generally too high. (I work with Lithium and Ni-Mh batteries for a living and any time I see a lithium cell read over 4.25, I am EXTREMELY cautious with it's handling and treatment.)