To have a single image span across displays, you may need to disable the option in Desktop & Dock settings and then use a third-party app or specifically sized slices for each monitor.
: Similar to Unsplash, this offers free stock photos with landscapes and abstract designs that are often wide enough for dual monitors. 2304x864 Two Screen Wallpaper">
: Provides high-resolution, artistic photography that works well for spanning. Many images are 4K or higher, which you can crop to your 2304x864 requirement. To have a single image span across displays,