There is a webpage in my current project, where the Page_Load event was always triggered twice. I realized that the problem occurred because of binding data to a ASP.NET ListView.
After researching online for some time only I found that it's because of any Image control that does not set the ImageUrl. I am binding an image to the ListView, and I did not set any ImageUrl.
I just need to set the ImageUrl, that's all, and it solved my problem.
Reference: How Firefox Handles Empty SRC tags