You received this error message because one or more Transaction IDs were duplicated in the Sales Confirmation page. There is either an issue with the way you are sending us the Transaction ID or an issue with how we are recording the sale. In order to ensure accurate sales reporting we need a unique Transaction ID with every sale.
Please ensure that you are passing us the Order/Confirmation number from the sale. If you are unable to pass us this information, please pass us a unique or random number instead. Click here for more information about the Criteo OneTag on Sales Confirmation page.