Why do you think Al chose Dolly after Trixie as bed companion/silent confidant?
Dolly was so different from Trixie. Do you think that was the point? Al wanted someone who wouldn't remind him of her? Did he want to move on to someone he didn't think he'd grow an emotional attachment for, that he considered slow next to quick Trixie (a slower girl might not be as quick to leave him, either)? Or is it as simple as him finding her the hottest of the girls in his employ? Odd, then, that he'd first turn to Trixie, who was the opposite of Dolly's type physically; it really was probably Trixie's grit and intelligence that attracted Al even from the start.