Thank you for this information. To be clear, I only use the larger, thicker cable. I'm assuming that is what you are referring to. I only use the shorter, thinner cable for connecting my phone to the controller, never to charge. I have also used the cables that come with my wall chargers. I have one from ANKER, NEKTECK and I just recently bought a 200W WOTOBEUS charger. None of the cables nor the chargers will charge the batteries in parallel, i.e. at the same time. And even when I use the Skydio 2 cable with any of these chargers does the Dual Charger charge two batteries at the same time.
I'm wondering if when anyone sets the batteries on the charger, they actually pay attention to what is happening to the lights on the batteries rather than just walking away. I have observed that while both the batteries have the first light charging on the battery, only one battery will illuminate more lights as time goes on while the other battery will not increase the number of illuminated lights until the other battery is completely charged.