The script below will find duplicate files (files with the same md5sum) in a specified directory and output a new shell script containing commented-out rm statements for deleting them. You can then edit this output to decide which to keep.
OUTF=rem-duplicates.sh;
echo "#! /bin/sh" > $OUTF;
find "$@" -type f -print0 |
xargs -0 -n1 md5sum |
sort --key=1,32 | uniq -w 32 -d --all-repeated=separate |
sed -r 's/^[0-9a-f]*( )*//;s/([^a-zA-Z0-9./_-])/\\\1/g;s/(.+)/#rm \1/' >> $OUTF;
chmod a+x $OUTF; ls -l $OUTF
