[gamez]

you have to give each WNDCLASS a different name and use it when you create a window.

wc.lpszClassName = "MyWndClassName";
wc2.lpszClassName = "MyWndClassName2";

ghMainWnd = ::CreateWindow("MyWndClassName", "MyWindow", WS_OVERLAPPEDWINDOW|WS_VSCROLL|WS_HSCROLL, 0, 0, 300, 300, 0, 0, ghAppInst, 0);
ghSecWnd = ::CreateWindow("MyWndClassName2", "MyWindow2", WS_OVERLAPPEDWINDOW|WS_VSCROLL|WS_HSCROLL, 300, 0, 300, 300, 0, 0, ghAppInst, 0);