If I have 2 {ethereal armor} on a creature. Will it double the amount of +1 for each enchanment I control?
Yes, they stack. Each Ethereal Armor applies separately, so If they're the only enchantments you control, each one says "Oh, you have two enchantments. Have +2/+2.". Since you have two, you'll get a total of +4/+4. Then if you have a third enchantment, they'll both bump up to 3 and give you +6/+6 total.
Ok. I thought so. Thanks