What do you have set for homepage?

Are you saying the page loads, then reloads? Or is it loading a second tab/window?

https://support.mozilla.org/en-US/kb/how-to-set-the-home-page

Type about:config<enter> in the address bar. If a warning screen comes up, press the I Accept the Risk button. At the top of the screen is a search bar. Type browser.startup.homepage

What is the value? Right-click and select Reset to restore its default value; about:home

If you have set a custom homepage to a specific URL, does the URL in the Firefox location bar change when the page reloads?

Some websites will redirect you to a different page under certain circumstances. For example, if the website is available in multiple languages and you have entered a URL that doesn't specify the language, the website may reload the page when it automatically detects your language.

I would recommend that you copy the URL from the Firefox location bar after your homepage reloads and paste it into the Firefox homepage setting to eliminate the possibility that the the page is reloading because the URL is not complete.