Memory Size in Icinga2 Monitor Dashboard not match real Windows Server memory size

My Icinga2 Dashboard showed memory size not matched our real windows server memory size.

For example, our real server memory size is 16 GBs, but Icinga2 monitor dashboard showed 28 GBs total.

image

I checked NSClient++ config file (nsclient) , below is info relate to memory from config file :

I also checked our script from Icinga2 Linux Server, here is info :
image

Looks like they all matched, why the dashboard not monitor the real memory size ?
Anyone can help about that ?