The RX200 is notoriously bad at "balancing" the charging of the three
batteries. You will end up with one battery being more fully charged than the other two, which can lead to problems as one or two batteries will be worked harder than the other(s). Most people recommend NOT charging the batteries internally and instead using an external charger, but if you must do so, then at least you should take the batteries out and rotate them each charge cycle so that they still wear evenly.
That said, you shouldn't have any
additional problems using a 2A wall plug instead of 1A. Amps are "drawn" by the device
from the wall adapter, not "pushed" into it
by the adapter. Using a 2A plug will not "force" two amps into the unit; rather it will make two amps
available to the device,
should it be capable of using them. If it is capable of charging at 2A, then it will charge the batteries roughly twice as fast as at 1A.