Hi everybody!
This is my first message on this forum, so I'm sorry if this is not right place to open such topics.
My problem is as follows: I'm running web site which main feature is a large photo gallery. This photo gallery is updated continuously with new images and as you may suppose there might be lots of duplicate files accumulated so far.
I'm aware of various duplicate detection/removal software, but the point is they can be installed and run only at my local machine. So to solve the problem I need to download whole my gallery to local drive, run this tool locally, find and remove all dups, and then upload gallery back to server. Such solution doesn't work for me at all.

May be you're aware of something different that may help me to find a way out of this...

Do you have access to your web server via ssh?? The way I would do it is run command line routine to delete duplicates and it wouldn’t require transfers to a local machine (which would be a extremely inefficient way to accomplish it).