Plugin hook called twice

Hello, this is the first plugin I am devloping and I think I made some mistake calling a function (of the plugin) from the theme, because when it is active a hook is called twice :S

Here some simplified code:

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In this way the comment_text hook is called twice, if I do not run the get_rating function (called from the theme), it is just called once..

So what’s wrong with this??

Thanks!