Because it represents what the movie is about
Once upon a time
If it’s antiquated language, fable, or folktale
Mr. Frank says this line when they are all fighting.
He is saying that they don't need the Nazis to destroy them. They are destroying themselves by fighting. In this scene, they were fighting over food, which was certainly important -- however, Mr. Frank is saying that the good of all must be considered before individual needs.
Mr. Frank is saying that in order to survive, some sacrifice must be made, and the fighting must be stopped.
Based on this excerpt, it is reasonable to conclude that neither twin could die because they were immortal gods. The excerpt tells us that none of brothers died, and also it points out that they are the creators that once stepped on separate paths. They are still alive, but not in the sense that we are used to think. Each one has its duty and now they both look at the world from different sides.
