It is a non-linear map which have many paths to take and reach the end. The point is, that you play a map one time and you are happy. Then you have a little break in Portal, because there aren't any new released maps for some time. But the answer is here: play the Deja-Vu again, but choose a different path with different puzzles. You can choose freely the way that is going to lead you to the end. Thats it!
This will be the full version of the Aperture Deja vu mod. What is fixed? Some bugs. better boss battle. better boss battle ending. Save's at the boss battle. No more error when try to launch the mod. If any more error will be discoverd, please tell me