You need to set the concept of "bot accounts" and "alternative accounts" apart.
"Alternative accounts" are the accounts that were created by a player in order to supply his main account with resources. Such accounts are always operated manually by users.
"Bot accounts" are often dozens, or even thousands of accounts owned by one person for the purpose of selling in-game resources. The lifetime of bot accounts is not high as they rarely reach lvl 30-40 in the game.
We carry out various investigations based on different criteria in order to find bot accounts and ban them (our automatic BotCheck system has already banned more than one million bot accounts). We have also released different restrictions in order to limit the activity of bot accounts in the game (trading and gifting systems limits, limits to upgrade Alliance Beacons). Checking the validity of the session in the game allows avoiding situations when accounts of real players are stolen by bots for their further usage. Game administration is and has always been in favor of fair gameplay and we are still developing new limiting features for accounts that are identified as "bot accounts".