I am promoting Wallch. Wallch is a wallpaper changer for Linux. If you do not like seeing the same wallpaper, then install Wallch (https://launchpad.net/wallpaper-changer) and select a folder containing the wallpapers. Wallch can choose a wallpaper randomly over a set period of time. Wallch is stable, and its development is still active. Wallch even has its own dedicated beta-tester. The other wallpaper managers for Linux cannot say that.