As Mac pointed out, becket dances can be more complex/confusing. Removing a need to separate you from your partner at the end of the dance, allows for some choreographic flexibility. All the same, most beckets are not notably more complex/confusing than most improper contras.
My guesses are: 1 - this couple had a bad experience that they associate with 'becket formation' rather than whatever confounding factors go into making a dance experience pleasant or unpleasant 2 - was this a contra event (all duple-minors all the time) or a more varied program? Maybe the couple doesn't like contras much? 3 - Maybe they are confusing it with some other formation (sicilian, 4 face 4, squares, triplets, etc.)