The memory compatibility is determined by the processor’s design; this does not mean that because of an issue during the manufacturing process, the processor is limited to a specific maximum memory amount value; the main reason of why the limitation, is merely marketing decisions in order to cover the different market segments.
Furthermore, processors that come installed on mobile systems, such as laptops, notebooks, etc… are tray units. These processors are sold to the different system builders, for them to be able to customize the processor as they wish for them to be able to integrate it on the system they have designed. Due to this, the specifications of the processor might vary from vendor to vendor.
From our side, the specifications publicly available correspond to the manufacturing design. If the processor from your system was not customized to support 4GB in total, the system might be able to work; in the mid time, the processor will be forced to run at higher specifications for it to keep up with the memory settings. This can provoke an unstable environment (system hangs, blue screens, restarts, etc) or even a processor failure in the future.
You can always check and confirm the manufacturing specifications at the processor data sheets, page 10: http://www.intel.my/content/www/my/en/processors/atom/atom-d2000-n2000-vol-1-datasheet.html#iid=5819
Our best recommendation at this point, would be confirming memory compatibility with your system builder.