First of all, you should probably add a 'use strict;' at the top of your code. It will show you a couple of problems with the code you presented above.

Second, if you are having problems with data structures, and they are not doing what you want, use Data::Dumper to see what is actually happening. Add the following code snippet after you have built your data structure:

use Data::Dumper;
print Dumper(\%newhash);
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When I ran your code with this, it gave me the following:

$VAR1 = {
          'IP' => [
                    'value1',
                    'value2',
                    'value1',
                    'value2'
                  ]
        };
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So the code is not doing what think it is doing.

I hope that gives you enough to continue.

- Cees