That would probably be the case with two cards as well but it doesn't really matter, both outputs put out audio and video so you can put them in to an audio or video device.Maybe people with SLI + multi-monitor setups can answer this? I remember reading once that a single card with 2x HDMI ports cannot split the audio and video between the two different HDMI ports. Unsure if that inability extends to dual cards.
It's different for the outputs of AV receivers for example. My receiver (other room, living room for movies) has 3 HDMI outputs but wouldn't be adequate in my computer setup as one only passes through video, the othertwo video with stereo sound. The HD audio signal doesn't get passed through.