Best way to combine two similar document I have f.ex.: two news-articles that report the same event. However, these two text are similar BUT not the same. I would like to combine these two texts creating one text that contains only the most "relevant" information.

I was thinking to check the texts paragraph wise on its "information value" and then only combine the paragraphs that are the most "relevant".

Any suggestions on an approach how to do this? Any research papers about this topic?
Your description could corresponds to the NLP task of summarization. This is an active field of research: https://scholar.google.com/scholar?q=text+summarization

A much simpler option is to only extract sentences from both: in this case the goal is not to produce a text which reads like a story, just an enumeration of sentences.

Even in this case you will have to define how to measure "information value", this is not easy afaik.