Coronation Street fans mistook a new character for an existing troublemaker on the ITV soap on Wednesday, before realising their error.
While some didn't make the mistake, they couldn't believe how alike the two separate actors were.
Many had to double take as Sam Blakeman actor Jude Riordan was joined by his real-life brother for some scenes, which he soon announced on his social media.
His sibling Zach played fellow youngster Oscar on the ITV soap, seemingly as a one-off, for the episode.
But fans were stunned when they realised this, as some had thought it was an existing character on the show in the scene.
Many viewers mistook Oscar for David Platt's teenaged son Max Turner, played by Paddy Bever, and took to Twitter to share their thoughts.
One fan said: "I thought that was Max for a second tbh," as another wrote: "Why does Oscar look like Sam’s cousin Max?"
A third viewer added: "Nice he looks like Max," which was agreed by a fourth fan who tweeted: "He does look like him!"
It was after the episode that Sam actor Jude revealed all on his real-life brother making a cameo alongside him.
Sharing a scene from the soap, Jude posted on Twitter : "When it was bring your Brother to work day. Sam smashed Oscar out of the bistro. BEST DAY so far @itvcorrie #bubblebrothers #samvoscar #corrie."
It was seemingly a Covid related decision, with Jude writing "bubble brothers" in the tweet - with the siblings obviously being in the same household.
Jude was thrilled to be alongside Zach, posting an image of them together on the set on his Instagram Story, writing: "Showing my brother the ropes."
He also revealed they were no stranger to going against each other in chess, telling a fan: "He plays a bit irl so we play together at home."
Viewers took to Twitter over the moment and Jude's confession that he and the actor playing Oscar were related in real life.
One fan said: "Good for you, nice to see Zach have a small part in your corrie experience."
Another said: "Didn't realise that was your real brother @JudeRiordan," as a third said: "Wait…that’s your brother?"
A fourth viewer commented: "wow how lovely!! I didnt catch all the scene but saw him looking a bit intense and not sure if he actually spoke in the end haha aww fab having a scene together playing Chess Rivals!! Will have to watch again on Catchup."
The comments kept coming too, with a fifth viewer tweeting: "So glad Sam won yippee! Didn't realise that was your brother how cool is that taken your brother to work," and another adding: "Oh Cool your real life brother?."
Got any theories or thoughts on the storyline? Let us know in the comments section below.
Coronation Street airs Mondays, Wednesdays and Fridays at 8pm on ITV.
