SW Duration paint - OK to thin with water?

I just hired a contractor to paint my house. I had purchased Duration exterior latex in advance. The contractor wasn't familiar with Duration and thinned it with water, probably by 15-20%. The label, which he didn't bother to read, clearly says "do not thin". I probably should have reminded him not to thin it beforehand.
He also thinned the SW A100 primer I supplied, and as a result, he had to use a lot more of the (thinned) Duration to get a decent coverage.
I'm wondering if the paint has been compromised and if the benefits of Duration are now gone, compared to a cheaper paint. Would it help to add some unthinned paint to it to thicken it up? Or perhaps SW sells some kind of concentrated paint to use as a thickening agent?
Or can this problem be solved by just applying an extra coat? I just hope I didn't waste a thousand bucks on paint ;)
The good news is that he only did the eaves and one wall so far.
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I agree with the other two responses. I'll add this: I find it strange and unexplainable that you did not call the manufacturer. Surely, there's a phone number on the label.
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GENERALLY speaking, latex paint can take a little thinning without SERIOUS consequences to performance. 20%, will definitely affect performance, however, because the concentration of solids in the thinned mixture is much lower. What you have is now probably around the level of cheap contractors paint. This can be made up with an additional coat of unthinned paint.
Negotiation will be a pain, but you paid for the performance of duration finish, and because of his action, he should eat the additional cost of providing you with a finish of that performance.
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