According to an email from Mobage, the number of players being banned seemed high since they didn't do December bans from the Holiday. This same player who was emailed addressed the fact that he had accounts on different devices in which Mobage responded that after a quick lookup they could tell he had X accounts on that IP and that it wasn't an issue.
Although the email didn't give specifics they did mention that members of one particular order were found to be sharing devices but most were linked to massive amounts of feeders, in some cases over 1000 feeder accounts.
The issue apparently is not on multiple accounts and there is no set policy on multiple accounts. Instead the problem is when people use multiple accounts to EXPLOIT the game. For example, having 30 feeders to support ten mains is.
That being said, a player who has authenticated his accounts on his personally owned devices, probably won't be punished.
Decided to update people at the urging of an Order mate.