At about $80, the Pearstone Dual Charger charges two batteries simultaneously, utilizing battery plates for different brands. One charger with plates for a variety of camera systems allows charging many types of batteries, even to charge two batteries from two different systems simultaneously.
I tested the Pearstone Duo Battery Charger for Canon LP-E6 with two Canon LP-E6 batteries (for 5D Mark II). I liked the fact that it gave a very bright LCD readout showing capacity and voltage, though this sometimes showed 0.00% after charging a battery to full— a bit disconcerting! Still, the charging seemed to work fine along the way.