Hi lou31,
We haven't heard of ads becoming linked between orders in the way you describe. This sounds like a question for our support team. I see in your other post that your mail to support got bounced - please let me know which support email address you used so I can help figure out why this happened to you. In the meantime if you could send your account info and the orders where this happened to blogadcr @ microsoft.com (without spaces) I can get a support ticket opened for you.
Thanks!
Carolyn