Very good point, and I imagine they do things like that to allow different running lengths as required too. From memory weren’t all the Chasers wearing similar black and red clothing? I imagine they’ll be wearing the same tonight if this is the case.
The Chasers have a costume for the usual show, so I don't think there's much relevance to that. Bradley Walsh has a variety of outfits usually, it's his that's worth paying attention to.