Three of my phals are growing two leaves at the same time, one is even spiking. It's it normal for a pal to grow to leaves at once. I have a lot of new growth, and the other phals in the same location and conditions is exploding with growth, but is only growing a single leaf.
The plants are happy and energetic. What ever you're doing, keep doing it.
You cannot expect all plants to react the same to the culture you're providing. Almost any difference can affect how the plant responds - including genetics.
It's fine. As was mentioned, individuals of the same species or the same hybrid don't all behave the same way. Different species or hybrids don't behave the exact same way either.