Unfortunately, there is no way to turn off the Resend dialog when going back on a webpage. That particularly happens when there is a form or some kind of web page that needs to resend details to the server to get the information back from the Web Page server itself.

I get around that message by not using the Back button on websites that I know from experience are going to want resend information when I "go back", by selecting the previous page I viewed in the history drop-down on the Unified button, I don't get that "warning box".

Either that, or I open the link in a new Tab and then close that Tab when I am done with that page.