Is multi monitor supported with a Radeon X1900 GT in a PowerMac 11,2?

I am asking because I only see a mirrored image of the first monitor and I only have a RadeonX1900GT in my mode list in screens preferences, no RadeonX1900GT.1 which should be there, as far as I understand.

I have one port of the gfx card connected with a hdmi adapter to the hdmi input of the monitor and the other port to the dvi input of the same monitor. The screens on both inputs are the same.