Both screens 1600x900? Mine are not 3200x900 but it's the same aspect ratio so shouldn't matter.
I'll dump some of my own but as someone who has had 2 24 inch screens for a while I'd say you're best off searching for 2 matching wallpapers instead of using one. Most of the time in dual screen wallpapers the focus is awkwardly in the middle where the gap is.
