These are tough questions, and ultimately I think the answers depend on what the norms are in your market, and what premium you can command over "Joe's Generic Painting".
I do a *lot* of Duration work because a lot of my business is in a newer part of town where the homes are just coming up for their first re-paint and homeowners don't usually change the color that much. More important, many of my competitors sell one-coat jobs. So the market in this part of town is conditioned to expect that. So I position two-coat jobs as being for either old & weathered, new construction, or drastic color changes. Trying to sell two coats always would put me at a huge disadvantage and price me out of a *lot* of work. So I sell one coat jobs using Duration. It's either figure out a way to make it work with some kind of decent margins or don't do many exteriors.
So on to how to price one coat Duration jobs. One school of thought says just price it like you would any other job (Labor, Materials, Overhead, Profit). In this case, the materials cost will be higher, so your price will reflect what you need to cover that, and then labor, overhead, and profit are what they would be anyways. Another school of thought says that you should be able to charge a premium for the value of the greater life expectancy of the better paint.
For example, if your market allows, you could sell along these lines: "Mr. Customer, I have two proposals for you. The first is to paint your home with one coat of XYZ paint at a cost of $3,000. I know from experience that this will only last about 5 years in this climate, so your per year cost is $600. My second option is to paint one coat of Duration at $4,500. Forgetting the lifetime warranty, let's say this lasts just 10 years. Your per year cost is now just $450 *and* you won't have to go through the disruption of having your home painted again as soon. Don't you agree that is worth the premium?". Note that I said "if" your market allows. If all of your competitors are simply tacking on the increased metarials cost, you will have a hard sell using this approach.
One last thing to consider when pricing one coat jobs vs. two coat jobs: You will complete the one-coat job faster and move on to the next job. So be sure to look at the big picture over time, not just the fact that you make less on each job. Be sure to show a profit on each job, but don't put too much pressure to make a killing on every job. It may work out that an "acceptable profit" on lots of jobs works out better for you than a killing on only a few.
And again, all this needs to be considered along with what your market will allow you to do. I'd love to get a 50% "value premium" for Duration jobs, but my market just won't allow that. Yours might though.