Remove duplicates, as long as you have it.

Greetings. I have this link file which has been active for quite a while, but the problem is that when I used a "admin" program to manage the links (admin.php) it kinda wrote the file multiple times, which means that it has sorted the file and added multiple instances of the lines. How I managed to create it? Well, by using the free linkadd/linkmanager PHP script. Anyhow, what I need is how can I remove duplicates that are sorted in arrays? Or does anyone of you has such a script or C++ program, so you could sort the file for me or something? Thanks - Richard