The simplest way would be to count the frequencies of all names and then take the top n of these. Loop over all the names, use each name as a hash key and as the hash value keep a counter of how often you encountered it. The value will be undefined for the first occurrence so the ++ operator correctly assumes zero instead.

my %freqs;
$freqs{$_}++ foreach(@filenames);
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Then sort by frequency, descending (compare $freqs{$b} with $freqs{$a} instead of the other way round), and take the first say 10: