>>3047You are right in that it will be confusing, but there are a few ways to identify them. For both Satori and Koishi, the eyes on their chest are much flatter, I don't have a good close up reference photo though so I could be wrong.
Satori's heart on the headband is much flatter and appears to be more green than yellow, the same goes for the hearts on her shirt. There are also less details on her shirt, on the standard there is a line with dots on either side running vertically in the front, but on the Ichinana there is no such similar thing.
I haven't been able to as easily find any other distinct differences on Koishi. I'll ask a friend if they got any closer photos which I might be able to investigate further.