Hi personaladriana,
the animation for the eXtro Background slider has been designed to constantly repeat, so the zoom/tilt effect can display correctly.
You would have to completely change the animation if you want to have the first image to be animated and the second to be a freeze frame.
All animations are defined in the module file, but please be aware that you need knowledge about CSS3 / CSS3 animations in order to change it.
maike