Combining two 'identical' files into one.

Hiya,

So I am working on an After Effects file containing an animated character that has various animations. The project contains comps for those animations and ofcourse all kinds of footage to act as limbs, clothes, and other accessories. My colleague is working in a copy of the same file, as is logical with a copy it contains the exact same footage as the original but he just uses them to create different animations.

Now we want to merge these two files together so we have all those animations in one file, but logically we don't need all the footage in that combined file twice (which happens when you simply import the project). So how do we do this? Is there perhaps an easy way to get rid of all the excess footage and replace those with the ones already in the file where it's being imported to? Without having to manually replace the footage one-by-one?

I've been trying to find an answer to this for the better part of the day, so hopefully someone has the answer.

Cheers.