Two triggers, same ControlID

Question

I have a updatepanel, inside them a fileupload. To make this works I create a trigger for updatepanel (<asp:PostBackTrigger ControlID="btnImport" />)
This works fine but now I wish put a UpdateProgress (out of updatepanel) but I can´t add (<asp:AsyncPostBackTrigger ControlID="btnImport" EventName="Click" />)

So, how I can solve this problem? If the code is just the first postbacktrigger it works normally, if I add async bummm, the script give me a error.