Memory leak while load and free library

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MFC

I found a memory leak while loading and freeing library contnuously.
When I see the task manager, the memory grow up for this application. I have no memory allocation in my DLLMain. This is the sample code

for (int i=0;i<500;i++)
{
hInstance = LoadLibrary("MySampleDLL.dll");
if (hInstance !=NULL)
{
FreeLibrary(hInstance);
hInstance = NULL;
}
}