Ooohh, so you can't just, say, have 4 Ratings each of Fire Resistance/Insulation/Nonconductivity on your Armoured Jacket, then slap Chemical Protection on your Fashion Cloak that you wear over the Jacket?
Or you can do that, but if you have Chemical Protection on both Jacket & Cloak, you only use the highest value instead of adding them both together?
I've always played it where my main armour protects from tasers and fireballs, with an acid-rain-resistant poncho over it.