If your code is correct until the 'grep' (and I think is correct), you should have an array of hashes like this:

@images = ({Name,'a',Size,2},{Name,'b',Size,3},{Name,'c',Size,2},{Name
+,'d',Size,3});
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You can verify which files have the same size as others (the list of duplicate files) with this grep:

my @duplicates = grep{$c{$_->{Size}}++ && $c{$_->{Size}}>1}@images;
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I consider that a file is duplicated when I have checked another with the same size. (I check only the size).
and this is only to check:

for (@duplicates)    {
    print join " ", values %$_, "\n";
}
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Note that I've changed 'name' for 'Name' and 'size' for 'Size' because -w warns
'Unquoted string "name" may clash with future reserved word '

I hope it can help you
Hopes