Hashes cannot have duplicate keys. The example you gave actually reduces to a single key/value pair (%events = ( '8-15-2006' => 'Jen' )). It looks like you want a hash of arrays, where the key is the date and the value is a reference to an anonymous array that contains the names of the winners:

%events = ( "8-15-2006" => [ qw( Jerry John Jen ) ] );
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See perldsc for more information about complex data structures.

For printing the results you may want to look at one of the templating modules that are available, which will allow you to separate the code from the presentation. Template Toolkit is a popular choice, but for something this simple HTML::Template would easily do the job.