He who pays wrongly pays twice

In our colloquium there is a phrase “he who pays wrongly pays twice”.
Conduct a search and research for two examples in which a business transaction was underpaid.
Write an essay providing the following information:
Identify the parties and the industry.
Identify the business transaction between the parties and the terms to which the transaction was subject.
Identify the form of payment agreed or established.
Identify the form of payment adopted by the debtor.
Discuss how and why the debtor underpaid.
Identify the consequences of having made the wrong payment.