while ($name = shift @inp_names) {
   for $canon ((canonical($name))) { #extra parens force list
      # add $name to an anon array, stored under the $canon key
      push @{$possible_matches{$canon}}, $name;
   }
}

for $canon (keys %possible_matches) {
   print "matches under $canon= ",
         join(',', @{$possible_matches{$canon}})
         "\n";
}
# for illustration. untested