It's really hard to say...time may tell, one fine day when all those pullets lay on the same day so you can compare.
Coating and bloom color can vary some, speckles can vary more...but shape of egg usually remains pretty consistent.
I've had a few groups of birds I could follow pretty easily....but now I have too many, and too many that are similar to bother...it'll drive you nuts!
Short of keeping birds separate all the time, or using trap nests, it's pretty hard to follow the variations of one birds eggs.