According to Jim Recap: Dana Dates Jim
Despite the title, Dana doesn't literally date Jim. She does, however, date Hank (James Michael McCauley), who looks a bit like Jim, dresses like Jim, and most certainly acts like Jim. So it's a pretty apt comparison. The only problem for Dana is that she can't see it, while everyone else can. Actually, that's not the only problem, though it is the first problem.
The second problem is that she mentions to Cheryl all the bad things about Jim, which gets the two of them in a fight. That in turn means that Jim has to turn into the new Dana, so that he and Cheryl go out shopping and he has to hear about her day and all those things that he just doesn't like very much. So it's in Jim's best interest to make things work out.
But the third problem is the worst. At a Halloween party, both Hank and Jim are dressed up in the same outfit (I told you they were alike), and when Dana sees Hank head to the kitchen, she decides to sneak up behind up and grab his butt. That's when the third problem comes along. It wasn't his butt she grabbed, and that's when it hits her that maybe Hank is a bit like Jim.
She breaks up with him.
In the end, Dana and Cheryl make up, which makes Dana realize that maybe the outer package isn't everything - it's what inside that counts, and that is what Cheryl loves about Jim. So Dana goes to talk to Hank and see what happens. It doesn't look like we hear from Hank again, so I guess it didn't work out.
