Really I don't know if they have banned any but nor can we say that a botnet has done mining on Magicoin. I only say on theory that can be prevent an exccesive mining of a massive botnet over any coin. Obviously the botnet will get some coins until this be detected.
I am a very active member of the XMG Coin Magi community and keep a constant eye on POW mining activity. I have made representations to mining pools on two occasions where suspicious activity has been detected. On both occasions this resulted in the suspicious activity being stopped and the perpetrators banned from the mining pool.
Obviously, even this pro-active monitoring cannot prevent all abuse, but XMG is a hybrid POW/POS coin that resists "50% attack". There is also the unique XMG block reward algorithm that reduces the POW block rewards to near zero if the the coin is being over-mined, so a very large hashrate from a server farm or botnet for example will gain next to nothing in returns. This is the reason why most XMG mining pools now apply a hashrate limit.