The Hungarian stars impressed the judges on Saturday night with their acrobatic basketball routine, but it's been seen on telly before.
The group took part in a similar stunt for Simon's gameshow Red or Black last September, which was hosted by BGT presenters Ant and Dec.
One of the contestants on Red or Black told The Sun “They were pretty good at it. You don’t really see anything else like it, so that’s how I recognised them straight away.”
He added: “My girlfriend thought it was pretty odd to have Hungarians on the show but when I told her where I’d seen them she flipped her lid.
“I’m pretty angry too — I don’t think it’s right that they’ve already been on a Simon Cowell show before.
“It would be all right if Simon had come out and said he’d seen them, but he didn’t.
“I feel cheated and I feel very bad for the contestants who did not get through because Face Team did.”
A source at BGT however told the newspaper: “Face Team did appear on Red Or Black but they were a very small part of the show. Simon was in the US at the time and was in no way involved in them being on the show. Face Team were booked by ITV Studios, not Simon’s company Syco.
“There’s nothing to stop an act that appeared on Red Or Black performing on BGT.
“Simon didn’t say anything like ‘I have never seen this’ like the other judges and in fact said they had to improve.”