Bantam hens laid two very different sized eggs...

Hello! I have two bantam hens that are about a year old now that just started laying eggs again... the first one I found (a couple weeks ago) was very soft shelled but of regular size, and this morning I found two eggs, one "normal" size, and one that is barely bigger than my thumb nail... I don't know if one bird laid both, or if one came from each of them... is it normal to see such variation in egg size from the same breed? Or is this just because it is the first few eggs of the season? (they didn't lay all winter) thanks for your help!!!