Back button overlay iframe's content in Safari

We have a problem in safari, when we click back button after some action or simple navigation on site, <iframe /> content are not always created correctly.


For example, on page, we have installed <iframe /> tags:

<iframe src="iframe1.html">content iframe1</iframe>

<iframe src="iframe2.html">content iframe2</iframe>


After back click button we have:

<iframe src="iframe1.html">content iframe2</iframe>

<iframe src="iframe2.html">content iframe1</iframe>


Sometimes, content of our iframe move in the other iframe.


How can I fix it?

Pls help!!!


Safari Version 13.0.5 (13608.5.12).