While I can not recommend rolling several nights in a row because of the potential consequences, before I knew anything about M when I was young and stupid God knows I did the same thing. I was fine, but our bodies are unique and can not say that you will suffer no ill effects, which is why I can't recommend it. But if you must...
I vote for the above answer. Your brain can not make much serotonin in one day, and taking MDMA squeezes a huge amount of your serotonin out. Lots of it will be reabsorbed to be recycled and lots will be destroyed.
Re-dosing squeezes just that little bit more out that was recycled. Rolling a second night immediately after will likely be very weak- although some people have definitely rolled a second night, chemically it's unlikely to be very strong because a percentage of that lovely serotonin was destroyed the night before. Dropping the second night will try to squeeze eeeeven more out, like the last little bit of toothpaste left in the tube.
If you MUST roll for the two nights, don't re-dose either night! The second night you'll be more likely to have enough leftover serotonin that might be able to get you going, if you re-dose you'll be getting the leftovers of the leftovers. 125mg standard dose on night 1, slightly higher (150 sounds good, as badrobot stated) the second night.
Stay safe and have fun! And props for buying a test kit and taking an interest in safety!
