You'll need two DC I think, one for each control.

BTW avoid to store DC, they are limited, scarce resource. Get them, do your stuff then relase them. The overhead is minimal and will avoid you nasty Win32 issues.

If you are familliar with MFC use a MDI application instead of Dailog based. You then write a single MDIView and instanciate it twice. You'll then use different two timer (one in each view) and implement drawing in the OnPaint() MFC handler.

Alternatively you can also derive your own Picture control and do the do the OpenGL stuff there.