Do "owed" and "due" mean the opposite?

Owed and due are closely related.

Owed, without more explanation, means the total amount of debt obligated to be paid by A to B

Due means the amount of debt that is expected to be paid by a given date (a due date) from A to B.

At times they are the same, at times due is a subset of owed. This assumes that the person owing is also the person from whom payment is due. In legal jargon, they are often used together in the phrase due and owing.

"Owed" and "due" can apply in either direction: You may owe the bank money or they may owe you money. In your example, I think they are just indicating that "due" here is a synonym for "owed", though broader context may indicate a more specific meaning is intended.

As Bib indicates, "amount due" is the amount that someone is obligated to pay as of a specific date, which may or may not be the total obligation.

The Wikipedia quote does not state "due" is opposed to "owed", but pertains to mean that owed and due are interchangeable. We all know the amount due to the merchant, is the amount owed by the customer. The amount owed, is therefore the amount owed by a merchant to a customer.