I just got the "Extra Effect" perk and enchanted my one-handed axe with Health Absorb+Soul Trap, but the Soul Trap is not working. After killing enemies i don't trap the soul on the gem. Is this a bug? It's possible to have the soul trap as second enchantment?
Soul Trap works just fine as an enchantment, single or double. One of my two daggers had a very similar set of enchantments. (I think I had one with Fire/Soul Trap as well) There's a couple of reasons why this might not work properly, though: