You had to have known this was coming. Assuming any of you are keeping up with Total Dramarama.
It was very obvious, and I'm sure that I wasn't the only person that knew they were Duncan's parents before it was said in the episode.
They look exactly like Duncan and the same as how they looked in Total Drama Island, except for the mom; however the only difference is her hair color, so they're canonically the same person. Most women, as they get older, tend to dye their hair blonde, regardless of their natural color or preference in order to hide their grey hairs. Of course, not all women do this, but it happens more than it doesn't, and I know that for a fact.
See? They look exactly the same, except older. The body forms and basic details are the same. Duncan's dad has glasses, a toupee, and different clothes as ten years older. Duncan's mom has her hair dyed blonde and is no longer the natural red head with different clothes as ten years older.
Here's the part that many people don't like that I will try to explain.
Duncan's family is made up of police officers and said that both of his parents were police officers in Island, but in Total Dramarama, his parents are entertainers for little kids.
That isn't that hard to grasp. Obviously, they didn't make it big as Bananas and Cheese, or as they got older, they got tired of doing it. So, either they were police officers prior to being Bananas and Cheese that took a break from police work to follow some weird dream OR they were Bananas and Cheese and grew tired of it or weren't getting enough money, so they both went to the academy and became police officers. Their own parents probably had expectations that they be police officers anyways, considering the pressure on Duncan to be a good kid and follow in his family's footsteps. Personally, I believe the first part. They started as cops and then tried out a different career as their kid was a little to try and connect with him more.
Finally, if any of you remember one of my previous theories, then here goes an addition to it!
If you refer to Part 89: I HAVE A CONSPIRACY THEORY/HEADCANON or whatever it's called, you will see the part where I say that Crimson is Duncan's little sister.
Well, by seeing Duncan's mom as a younger woman and in higher quality than in Island, I stand by my theory even more!
Crimson has red hair, Duncan's mom has red hair. Crimson has blue eyes, Duncan and his mom have teal blue eyes, so that's basically the same, and Crimson has the exact same skin color as Duncan and his dad.
Total Drama just continues to basically prove my theory here. Maybe some of you will even adopt it as one of your own headcanons as well. That would be so cool!
Anyways, the Bananas and Cheese plotline was hilarious because baby Duncan was losing his shit! It totally fits in canonically. It even sheds some light on all of their personalities and behaviors for the Island timeline.