#!/bin/bash
for backup in "$@"; do
 filename=${backup%%\~}  # prevent tilde expansion with escape
 echo Searching for "$filename" >&2
 if [ "$backup" = "${filename}~" ]; then
  if ! diff -q "$filename" "$backup"; then
   echo Not removing backup file "$backup" >&2
  else
   rm "$backup"
   echo Identical backup "$backup" removed >&2
  fi
 else
  echo "$backup" != "$filename" >&2
 fi
done