two submit buttons conflict

I have two submit buttons in my form with different names. And i have validation (jquery.validate).

When i don't fill all fields and press second submit buttons the form doesn't submit - so i fill necessary fields and click the first submit button. And i get two fields in post - first and second buttons.

What's the reason of such behaviour? I expect sending only first button in post, because i click on it. More than, if i click first button straight without clicking second, there is only first button in post.

Hope you answer my question.

Regarfs, Nikolay