It isn't an option in our server behavior. It would require hand coding.
You would check to see if the cookie had a value in an IF statement and add a comma before the value if it had a value, if not then you just set the value as it is done now. It is another issue that requires hand coding and I could help with in a premier ticket if you had difficulty pulling it off on your own. Something like:
<?php
if ("" == "") {
$newCookieVal = isset($_COOKIE['ViewedProducts'])?$_COOKIE['ViewedProducts']:"";
if ($newCookieVal) {
$newCookieVal .= ", ";
}
$newCookieVal .= $rsProduct->getColumnVal("ProductID");
setcookie("ViewedProducts", "".$newCookieVal ."", time()+(60*60*24*30), "/", "localhost", 0);
}
?>