Your code iterates over the keys and values of the hash one at a time, putting the result into $key, a scalar variable. Then it looks in a hash named %key... I think that what you really want is:

foreach $currentkey (keys %hash) {
  
}
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(If you're cool with $_, you can leave out $currentkey in that incantation.) I can't figure out exactly what you want in the comparison, though. $hash{$currentkey} will give you the value associated with the key currently in consideration. To get the hash value for another value, you can use $hash{'key_name'} if you are referring directly to a string value for the key, or $hash{$value1} if the variable $value1 contains the name of that key.