Supposed sources claim that Tulisa is bringing Posh Spice's exclusive brand down by wearing the outfits, such as the one seen on last week's live show.
Star magazine report that Posh isn't at all happy with Tulisa for 'damaging' brand Beckham.
"Victoria is very particular about who wears her clothes and she rarely gives out dresses unless it is to a close friend or a big Hollywood star," an insider said.
They continued, apparently being deadly serious: "She is fashion royalty now and dresses the likes of Julia Roberts, Gwyneth Paltrow and Kate Winslet, as well as other powerful and influential woman around the world."
And the supposed insider claimed that Tulisa was hurting Victoria's brand by wearing the dresses, given her 'urban roots'.
The source added: "Her clothes have to retain that exclusive quality - and while it's great that they are given a profile on X Factor, she doesn't want her dresses being brought down to high-street level."
Vote for who you want to win The X Factor 2012 below...
The X Factor 2012 continues tonight with the live final in Manchester.
Chris Maloney, Jahmene Douglas and James Arthur will be battling it out to be crowned winner, while there will be performances from One Direction, Kelly Clarkson, Rita Ora, Kylie Minogue, Rhianna and Emeli Sande.