Every bill I've seen says somewhere, "If you already made a payment ignore this notice". And you also have the option of calling them to tell you its been made and by what method. Some will accept the confirmation number at the end of your bill payment, but most times they say, "Okay great. Thank you. Anything else I can help you with today?"Guest said:
I do not trust using online banking bill pay as if they do not have the vendor as a partner then the payment gets generated as a paper check and snail mailed. This defeats the purpose and could arrive late in that case.