Hi Holly,
Yes it's normal for them to have their squabbles, as long as there is no injuries or severe bleeding then they are fine, every day they play out who is dominant over what which results in one being pinned down and squeaking.
Don't worry too much about the show, it wouldn't be the first time i've went to a hamster show and heard the faint squeaking of winter whites or campbells. If anything, being in unfamiliar territory will bring them closer as they'll curl up together to hide from the leering public who want to see how cute they are
Hope this helps, any more q's PM me