Can AMD and NVIDIA display cards work together on linux?

I know that two AMD graphics cards/two NVIDIA graphics cards can work together ,e.g. in xinerama/crossfire/multi-view. But if I have one AMD graphics card and one NVIDIA graphics card, can I use them together on one platfrom simultaneously? How can I configure it? PS. I am asking about the closed source drivers. Not the open source drivers. Did anybody try and success?