Problem in a 2 node types module

Hi!
I try to develop a module (competition) which define 2 new node types (competition-player and competition-team). So i define the two next functions :

function competition_node_types() { 
   return array('competition-player', 'competition-team'); 
 } 

function competition_node_name($node) {
switch (is_string($node) ? $node : $node->type) { 
     case 'competition-player': 
       return t('player'); 
     case 'competition-team': 
       return t('team'); 
   } 
}

And it works, but...
the field 'type' in the table 'node' in the database is limited to 10 characters, and 'competition-player' is too long. So I have change their name to 'team' and 'player', but this doesn't works. We must prefix names of the node types by the name of the module. Why? Is their a solution to my problem?