Several enhancement bonuses that all apply to the same thing don't stack, but enhancement bonuses that apply to different things do.
For instance, you could have a suit of armor with an enhancement bonus, and a shield with an enhancement bonus, and both would work.
The rule is that bonuses of the same type do not stack, except for dodge bonuses, untyped bonuses, and with GM permission circumstance bonuses. As Are mentioned, an enhancement bonus on armor (e.g. +1 full plate) works if you're using an enhancement bonus on a shield (+1 shield), but that's because one is affecting the armor bonus of the armor, the other is affecting the shield bonus to AC of the shield. Otherwise, no, enhancement bonuses don't stack.
Though my issue is, i cannot find the rules anywhere in the books... As i've mentioned in previous posts, my GM is a rules lawyer and he needs convincing. If you could please tell me where to find such rules, i'd be much obliged.
Best Regards
- Shadeworld
See page 208 of the Core Rulebook, bottom of the first column and top of the second column, under Special Spell Effects, subheading Bonus types.
Future note: try posting a question like this in the Rules forums. You'll get your answer faster :) I only answer basic questions like this one, the rules lawyers who will make your GM look like a lightweight are in there :)
Also the specifics of what you're trying to stack helps for rules questions. Like is it an enhancement bonus to Strength and an enhancement bonus to Armor? Or two bonuses to Strength?
Specific questions will get specific answers much more quickly.