Welcome back
People on the same IP are allowed to play the game, however in order to limit the amount of cheating (ie, multiing and/or farming), there is a "no interaction*" rule that both planets need to follow. This system is known as the Exception system, and you'll need to get into contact with the Multihunters to ask to be set up like this.
Join #multihunters on /server irc.netgamers.org
or
Fill out a
Support ticket, Topic as Exception and flag it as a MH issue, and they'll sort both of you out
.
*Whilst attacking eachother is strictly forbidden, it
is permissable to defend eachother once in a blue moon (like a week). As such, joining the same alliance or galaxy probably isnt the best idea.