Is it possible to mine with both (2) GPUs in headless mode? I've got a Mac Pro with two different GPUs in it—one is a new 5850 and the other is some old (stock) Radeon.

I'm wondering if it is possible to mine with both cards simultaneously if the OS is configured to be headless (i.e., neither card is used to display a GUI)?
I have tried the bitminter client for mining and it seems that both of my gpus are used.

You can try downloading it from here