I have a big hash. Some of the values in the hash are the same how do I do to add all the keys for the values that are the same?

An example of what I mean would be:

%hash=(10=>1, 20=>2, 30=>1 40=>2);

[download]

After the procedure it should look:

%hash=(40=>1, 60=>2);

[download]

If I want to check if a key exist in a hash I do..

if (exists ($hash{$key}))
{
do..
}

[download]

This i very confusing to me. To $hash{$key} should be the same as the value. Could someone explain.

And how do I check if a value exists? I can not reverse the hash since it has many of the same values.

Thank you for your help.

Code tags added by GrandFather

In reply to Confusion due to hash by tamaguchi

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