Thank you. I have rerun the php file with the correct three recordsets. This still behaves as before, i.e. after selecting/pressing each of the add to cart buttons, when you go to the cart there are three seperate entries, one for each button but all three are using the same database entries for their description, price etc, although the quantities do match the number of times the add to cart button was pressed.
I have attached a zip file containing the rerun php file and a screen grab of the Server Behaviours Panel.
I hope this is what you need to resolve this issue.