my page thinks that I clicked again my ASP:Button
By default the ASP.BUTTON always causes a form to be submitted to the server when the user clicks them. Use the HTMLButton instead. If you define it like this:
<button OnServerClick=" FancyBtn_Click" runat=server>
You can still process the button click on the server.
Also, using static (shared) variable isn't a good idea. If you need to maintain a varables state across post-backs use a ViewState to store the value in.