When someone hits their 'back' button to get to a previous page in a site, display a different image on the page to the one they saw previously WITHOUT randomizing the image itself?

For example, lets say the site had index.php and index1.php.

I visit the site and the first page i see is index.php.

Now i click a link which takes me to newpage.php.

I hit my browsers back button and get served index1.php.

Anyone know if this is possible to do?

Regards,

Lee