Yes, understood. Doing both cells in parallel will probably give a different ending voltage than doing just one of them. It could also wind up being even higher than one single cell (which I understand is the opposite way that you want to go)

It may also be possible to increase the charge rate , vary the lead length and/or size affecting the termination point if the charger works that way. It might also be posible to use a 4.1 setting rather than the 4.2 setting.