Think of it as this way. Moonlight referrs to light right? Darkness referrs to pitch black right?
When you mix the two, you get twilight, where night and light are both joined together, like yin and yang.
I kinda got an idea, because i had a huge flame argument back at a certain forum. so this name came up to balance my good side and my bad side >_>
a little dramatic though, but hey this was 2 years ago...