I can't believe for the second time I have been marked wrong for 'Due' instead of 'Duo", and it isn't even something that can be lazy!
No, but it is a legitimate English word, and in the past that has been the difference between "typo" and "error." Determining if it is something that can be lazy is above the computer's pay grade. :-)
I think DL is using "Duo" here as Duo the Owl's name. La lechuza, so Duo could be lazy -- or NOT lazy as the case may be!
And that makes "Due" an incorrect answer, not a typo.
Take care, keep on learning, have a lingot from me :-)