If the leaves are the same type, I wouldn't be too concerned about getting the wrongs seeds. It's pretty rare to get two different types of seeds in the same packet.

Think about siblings of any type, there are almost always variations in size. With tomato plants, I don't let it concern me.

More likely than not, the ones with smaller leaves will catch up with the others, and if they don't, you can plant the larger ones and give the others away or compost them.

Betsy

Thanks Betsy,
But I planted them all at the same time.
-TomAndJerryGardener

Not all seeds are the same size. Smaller seeds sometimes produce smaller cotyledons. Even some larger size seed will produce smaller cotyledons. It all happens way back when the seed was forming in the fruit it came from. It happens all the time and is not an issue.

It makes no difference, either to the plant, how well it will grow or produce, and it makes no difference when they were planted.

Dave

I think the answer to your question is in the other thread you posted right after this one called Mysterious plant. You are using top soil with weed seeds in it. That is also the answer to your other recent thread What's wrong with my tomato plants leaves. There seems to be a common theme here.