Can this be done? Does anyone do it?
You accept a job because they offer early and then get a dream offer in the spring semester…
Em…it is not something good to do. That said, you don't want to be a place you are less happy for the rest of your life. If you move a few years later, it is going to be more harmful to the department. I would say, take the new job and politely let the other place knows about your decision. Then, they can make offer to their next candidate ASAP. People are much more understanding than you think.
There are few posts on the forum regarding this topic. You really shouldn't find yourself in this position as you should withdraw from searchers once an offer has been accepted, but alas. Here are a couple posts on accepting offers and then continuing on searchers or considering other offers. Someone recently posted about potential legal repercussions, but I couldn't find it.
What babybrains said.
Once you accept a job you should withdraw from all other searches immediately.
Such a move will seriously hurt your reputation (and the world of academia is a very, very small world).
You could very well be sued.
In short, DON'T DO IT!!!
Been there, and actually done it. With no regrets. Yes, it may hurt your rep in the short term. And yes, it may put the Uni in a tough spot if they lose other candidates. But remember, this is a business and most Unis operate that way - they are equally likely to pull an offer. The fear mongering about you getting sued after withdrawing from an offer is just that — unless there is specific language in the initial contract you sign obligating you financially or otherwise, an institution cannot sue you to take the position or to recoop any expenses (such as travel). At the end of the day, you need to do what is best for you.
"At the end of the day, you need to do what is best for you."
Exactly. Academics have an irrational fear of doing this, but anyone in the private sector would consider you crazy for not taking the best possible offer when it comes around. Accept the job and keep on interviewing if there's the possibility of getting a better position.