You are right.
I was confusing 5E (mage armor is +3 bonus) with 3E (mage armor is +4 bonus)
questions:
Mage armor and dragon bloodline armor should not stack?
Does it mean they should also not stack with barbarian (con) and monk (wis) bonus?
So there can be only one effect for wearing armor or using "when not wearing armor you get a bonus"?

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