If you only have 2 chickens then don't worry about quarantine.
And they may be just fine. But just in case, quarantine is recommended for ANY new chicken or any coming back from a show. Since I have more, I'll quarantine mine. The guy feeding the peeps at our show said I should treat them for...
At our fair you:
a) Have the chickens blood tested at the door.
b) Leave them there the entire time.
c) Let the fair take care of feed & water.
d) Let the fair take up any eggs which are then donated to charity (Rescue Mission for our fair).
The you quarentine any birds you bring home just to...