in reply to Load a file into hash with duplicate keys

It sounds like you want a hash of arrays...

push @{ $hashOfStuff{$key} }, $newThing;

Or possibly a hash of hashes so you don't have to search the array...

$hashOfStuff{$key}{$newThing} = undef #That the key exists is sufficie
+nt
if (exists $hashOfStuff{$key}{$testThing})
{
    ...
}

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