u64 TotalSize = Chunk1Size + Chunk2Size;
void* base_ = VirtualAlloc(BaseAddr, TotalSize, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);

void* Chunk2Mem = (u8*)base_ + Chunk1Size);

//------ sometime later in the code -------//
if(!VirtualFree(Chunk2Mem, 0, MEM_RELESAE))
{
    Assert("deallocation failed"); // this never happened
}