If OpenGL has already been inited, it won't be inited a second time now.

desmume/src/windows/ogl.cpp

@@ -7,6 +7,8 @@
 
 extern WINCLASS	*MainWindow;
 
+static bool oglAlreadyInit = false;
+
 int CheckHardwareSupport(HDC hdc)
 {
    int PixelFormat = GetPixelFormat(hdc);
@@ -33,6 +35,8 @@ bool windows_opengl_init()
 	int						res;
 	char					*opengl_modes[3]={"software","half hardware (MCD driver)","hardware"};
 
+	if(oglAlreadyInit == true) return true;
+
 	oglDC = GetDC (MainWindow->getHWnd());
 
 	memset(&pfd,0, sizeof(PIXELFORMATDESCRIPTOR));
@@ -66,5 +70,7 @@ bool windows_opengl_init()
 		else 
 			LOG("OpenGL mode: uknown\n");
 
+	oglAlreadyInit = true;
+
 	return true;
 }