Thanks Jimmy,

It seems not double requests. Although every request shows twice in Nginx's log, in my backend (Tomcat)'s log, only 1 record for each request.

So I guess, my server doesn't received double requests, but just Nginx outputs logs double times.

The weird thing is in one of my Windows 2003 server the log is normal but in my another one, the log shows two times. The config files and code are totally same.

The only difference might be the versions of Windows 2003. It's really confused.

--
Allen