Strange image request causing servlet doGet method to be called twice?

I'm working on a Java web application running on tomcat. I'm having a strange issue that occurs with every request. It seems every request is being made twice but one of the requests seems to be an image request. This is causing the doGet method to be called twice for the same page request. Here is a screenshot of the chrome network console's image tab:

As you can see, there is a request under the image tab that is exactly the same as the main request. I verified that a duplicate request is received by the server and that it is happening in both Firefox and Chrome. Could anyone please suggest what the cause of this request might be? I know I'm missing something but I don't know what. I appreciate any help. Thank you.