Reading Green Lantern and confused

I had read a Green Lantern book called Wrath of the First Lantern. Now I'm reading a book called Green Lantern Volume 3 The End. The book starts out with Simon Baz and things that happened in his life, and how he got a Green Lantern ring. Now for the confusing part. The rest of the book is most of the stuff that was in the Wrath of the First Lantern. So why make two books that are almost the same? I have never come across this before.

GL books do this all the time. Its if you want just a certain series or a whole crossover.