I personally would implement the following:

• if the left part of the given URL (until a # is eventually found) is already known, the submitter is redirected to the already given link and a post karma point is given to both.
• If it’s a picture, check if it’s md5 checksum already has been seen and do the same (and also free disc space by deleting the newest uploaded pic).

I did something similar in bash scripting for my current job. I can eventually help.

I personally would implement the following:

• if the left part of the given URL (until a # is eventually found) is already known, the submitter is redirected to the already given link and a post karma point is given to both.
• If it’s a picture, check if it’s md5 checksum already has been seen and do the same (and also free spCe by deleting the newest uploaded pic).

I did something similar in bash scripting for my current job. I can eventually help.