dual monitors

[Don]

I use 2 monitors with my PC. I have one graphics card that can support two monitors. I read somewhere that when you do this, the video RAM for the card gets split for each monitor (ex. 128 MB VRAM split to 64 MB for each). Is this true? If so, say I am playing a game which gets maximize on my main screen (I turn off the other monitor), does that mean the game thinks I only have 64 MB of VRAM?

thanks