User blog comment:JmLyan/Duo, the Twin Magician/@comment-8267817-20130509155328/@comment-7481207-20130509172218

That would be a bit hard to balance. If they both had seperate HP bars and the clone got Duo's bonus health, then it would be far too easy to tank with him. While if it didn't get bonus HP, it would be practically wothless and die easily. And if Duo's total HP is split evenly between him and his clone, then everyone would just focus attacks on Duo as his clone can't operate without him and with 50% less HP he is ridiculously squishy.