I know this may sound silly but i will go forward. Last year i used the 210 Skip on my main player and this year the 255 on my alt! The Advance character CR showed again on my main player! Is this normal to happen? I thought that if you use the skip once you can't do it again.
The CR Advance should be available as long as that character is below the described number, although if you use it on the same character again no extra skill points can be given, so if you do use your alts (especially if they're of the opposite faction) I'd say using it on another toon is a good move.
If you already used it on one character, and it shows again on another, then that just means it is offering you the chance to buy the advance from the MP. And yes, it is normal.
