Hmmm. A feature request for the obj exporter would be to track hinges (or rails) and make sure they are unique within the export. i.e. if a hinge_1 already exists in a previous object, and the next object in the export also contains a hinge_1, then rename this next object to use hinge_n, where n is the next unused number. This would avoid the need to manually edit the files.

Mmmm, and what if you want them to act as one hinge? The current way works just fine, you just have to be carefull when combining multiple hinges. What I do is just create a copy and edit it for the 'next' hinge and then combine them. This way you can easily keep track of the different hinges.
Particularly handy when creating a dresser with 6 drawers [:)]
I just create a drawer, add the rail for deformation, and export the drawer including the rail. Import the first drawer to test. You can do that because the rail is included. If it's ok, copy the obj and mtl files and edit it for the next drawer. This is easy because you have just a single drawer to handle.
When all are finished 'insert' them at the correct position into the base of your furniture and export the whole thing. You can't test the other drawers by themself because they don't have the first rail so wait until you have tem all together and they should work fine.