A story should have a beginning, a middle, and an end... but not necessarily in that order. ~Jean Luc Godard
Why? What does that mean?
Well, basically, you need an exciting end at the beginning to get your reader reading. And you need an exciting end at the end to get your reader buying your next book. So, how does a writer have two endings?
Here's an example, the main character is found dead at the beginning of the book... it's shocking and the reader wants to know what happens. The beginning and middle discuss the event and reasons why and the ending describes the event.
Look at the movie/book - The English Patient... The MC is in a hospital. What!? Why? Well, then the movie goes on to relate what happens.
One of the best examples of the ending starting first is a movie entitled Vantage Point. The president is shot at the beginning and the rest of the movie gives different POVs as to what happened.
This is why I love writing, we have the freedom to break the rules.
What does this quote mean to you?