I'm looking for the title of a book series that plays in a distant future. Mankind has a galactic, space faring civilization that is past its prime.

If I remember correctly, this civilization was ruled by a royal family or dictator. The story is about two different planets. They are a "failsafe" in case civilization is destroyed. They are meant to locate the other planet and restart human civilization. One of the planets was specialized on technology, the other one I am not sure, perhaps politics and philosophy or something similar. The book series deals with the struggles of saving a dying human civilization and locating the other planet in order to enable this rescue of the galactic civilization. I remember reading this book quite a long time ago, definitely around 10 years ago but can't recall the name.