Is there a way to tell blender which images do not differ within an animation to render them just once? Question

I wonder if it is possible to tell blender to not explicitly render images in a given time range when they are not changing. So to say, if I make an animation and within the animation there are time intervals with nothing changing. E.g. with a keyframe at time 1 and the same keyframe settings at time 2 theoretically the image could be copied a number of times equal to the number of frames of the interval and does not have to be rendered each time.

Manual solution

Of course this could be done manually, but is some work to do with copying the images certain times, renaming the following images to consecutive numbers and continuing the rendering at the end of the interval.

Details

I save the images as png-files and would create a movie afterwards myself. I do have more constant intervals which are marked in the dope sheet by grey bars. I've simply made two keyframes with the same settings for the start and end of the constant interval.
This is not a straightforward process, but there is a recently released addon to do just this. The auther describes the details and provides a download on the link. 
The gist of it is that it renders a tiny version of each frame and compares it with the others to determine duplicates before rendering full size versions.

http://creativityhacker.ca/2017/08/08/dopplerender-a-turbo-boost-for-blender-animation-rendering/