Wow! You have a very valuable hen there. If a hen lays a double-yolker, it's a sign that she is being over fed, but in all my years with many species of chickens, I never heard of one laying more than one egg a day. Could it be that two other hens visited the same nest while you were gone? Just a thought.
Could be, or she visited a few times. Our first year layers lay two eggs most days their first season. No double yokes so far. We are inundated with eggs!