The Fraxel Dual is an excellent laser. The stretch marks need to be treated on the 1550 setting and it takes several treatments. The Fraxel Repair would be too aggressive and is not indicated for stretch marks. I have had great results with the dual as well as the Ematrix for stretch marks from pregnancy. Please be certain your dermatologist has a great deal of experience with the Fraxel laser.
Fraxel re:pair Laser is a much more aggressive treatment for stretch marks than the Fraxel re:store Laser. Depending on your skin type and healing response, the skin may stay discolored (either red or brown) for months following an effective treatment. Fraxel re:pair make real laser holes in the skin that need to fill in and heal vs. the Fraxel Dual laser that scrambles the tissue eliciting a healing response and skin tightening, but not actually making real holes in the skin. There is some risk of scarring when using the Fraxel re:pair laser on areas other than the face.
Fraxel Restore is the laser you want. The dual has two lasers in it. Make sure you're getting the 1550 wave length. It hurts more and you will need topical anesthetic cream.