Dunn is definately listed as No. 1.
But everybody knows TJ will carry on short ydg sets and goallines. In other words, Dunn for yardage and TJ for scores. Dunn does have a sore leg but is expected not to miss any regular season time. I doubt he will see much time in the final preseason game.
Dunn, in my opinion, is a good back-up for a three back league or as a bench player for those bye weeks. He is a good receiving back option like LT, but certainly on a much...much smaller scale. (I'm not comparing the two!) But, he pulled in over 1000 all purpose yds last season and I expect to see more of him this season.
PLUS, Duckett is also prone to injuries, often injuries that won't sideline tougher RB's tend to sideline Duckett, If you know what I mean. Bottom line, in my opinion, Dunn is a good option in deep leagues. His breakaway speed might give him some long TD runs taking away from TJ, who we won't see in too many 1'st and 2nd downs.