Is having a second account bannable?

You can have an alt, but if you start recreating at lvl 4 and have a myriad of accounts just to get easy prey, or you keep chaindying outside the map the get easier lobbies that is considered bad, ex ranked loosing on purpose to stay in gold for instance.

But to have two accounts, one for playing with the kids and one for playing with you team, or one for playing solo and one for playing with your team is just fine from what has been said earlier both on forum and at hangouts discord.