Rotate between different ad block types

Yes, use the following code for block 1

<?php
if (rand (0,1)) {
define ("AD1", true);
?>
AD CODE 1
<?php
}
?>

and the following code for block 2:

<?php
if (!defined ("AD1")) {
?>
AD CODE 2
<?php
}
?>

Make sure PHP processing is enabled for both blocks.

Or more universal solution for more blocks:

Block 1

<?php
define ("AD_BLOCK", rand (1,3));
if (defined ("AD_BLOCK") && AD_BLOCK == 1) {
?>
AD CODE 1
<?php
}
?>

Block 2

<?php
if (defined ("AD_BLOCK") && AD_BLOCK == 2) {
?>
AD CODE 2
<?php
}
?>

Block 3

<?php
if (defined ("AD_BLOCK") && AD_BLOCK == 3) {
?>
AD CODE 3
<?php
}
?>

Thank you!

You are welcome!