To make the story short, I was playing the game when my sister saw it and decided she wanted to give it a try. I then told her to create her own account and then I let her play on my laptop. So she played until her energy was drained. Then she was convinced that she wants to continue playing and she'll install it on her laptop as well. To my surprise, upon logging my account in, the energy bar hasn't changed, which means that my 40+ mist energy was replaced by her depleted 2 or 3 mist energy!
Why is this, and will I be able to get my mist energy back? By the way, my OS is Ubuntu 12.04 LTS, in case that information would be important in bug triage.
I remembered this years ago. It's probably to prevent your alts from pouring in their profits into your main.