Phantom highlight spot trouble in a swimming pool

I have a problem with my swimming pool spots in one of my project. I don’t understand why there’s a “phantom” highlight spot for each spots : a second spot appears at the position it’ll have if there wasn’t water/refraction effect. Is anybody knows the reason why ?


The link of the project :
http://www.blenderartists.org/forum/showthread.php?347472-ArchiViz-photorealistic-rendering-project&highlight=