By the way, if someone did it accidentally, will the inactive one be deleted?
If the account was never used, probably. Otherwise one may be suspended or I may attempt to merge the accounts together.
Are the ban periods calculated by number of additional accounts? For example, if someone has 4 accounts, which means 3 duplicate accounts, and he/she admitted to them, will the ban period be 3x8=24 days or just 8 days? Might want to specify that on the 1st post.
Currently the bans are not based on the number of accounts, but that might be something to consider. We might handle it like the bans - if you get banned once, then create another account, the ban time doubles.
Also, in the "admitted use" case, players have to come clean BEFORE the multiple accounts are discovered. There are about 20 accounts already being looked into with bans pending, so if you have one of those, you won't be entitled to the ban time reduction.