According to crucial, your laptop does take the 2x1GB for a max.
http://www.crucial.com/store/listpar...e%20A135-S2356
Usually memory is added by using matched pairs, when you mix ram, the result is always uncertain. It is also always a good idea to use the ram manufacturer's configurator, then buy the exact part number, either from them or elsewhere. That way the ram is guaranteed to work, some motherboards are pickier than others at what goes in the memory slots.