XML::Twig is object-oriented. first_child is a method which returns a handle to something. To get the value of the child element, you need to use the text method:

print "NAME: " . $install->first_child('name')->text() . "\n";
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which prints:

NAME: TEST
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There is a nice XML::Twig tutorial at http://www.xmltwig.com/xmltwig/, along with a handy reference page of all the methods.