Feats for "Jekyll" (1st lvl expert char)
Profession: Herbalist (with skill focus Feat -1st lvl Expert)
Knowledge (nature) (with skill focus Feat - Human)
Knowledge (arcana) (with skill focus Feat - Free feat from Weak flaw)
Craft (Alchemy) (with skill focus Feat - Free feat from Poor Combatant flaw)
"Hyde" (1st lvl Barbarian)
Improved Initiative (1st lvl Fear)
Weapon Focus- Unarmed Strike (Human Feat)
The important to stress is that while both personalities know of each other, they do not share knowledge of their abilities. Also their physical and mental stats will alter per persona (will keep same point build, but assigned differently).
I also think that if "Jekyll" gets hit by an emotion change spell, like enrage, and he fails the save, he turns into "Hyde" even if he has not lost sanity prior to it. Also, if "Hyde" gets hit with a calm emotion spell and fails a Will save, then he reverts back to "Jekyll".