The short answer is: no. It’s possible to deal fairly with both parties and still emerge with a better offer. First of all, don’t assume that the company you prefer is being miserly by offering less money. In the war for talent, different employers have different strategies. Some are prepared to put all their cards on the table right from the start; others prefer to leave room for manoeuvre. It doesn’t necessarily mean they value you less.
While two job offers is a nice problem to have (at least, it should be), care must be taken not to lose both of them through poor judgement (or downright greed). Establish where each employer stands regarding a deadline for your decision. If they know you are weighing up another offer, then they are likely to have potential second-choice candidates waiting in the wings, who may themselves still be out on interview elsewhere. If you are applying via a recruitment agency, your consultant should be able to buy you more time (it won’t be in their interests for you to come away empty handed).
Be specific. Don’t just say what the other party has offered without indicating if you expect your first choice to match or better it. So, say what you would ideally like. They may be unable to offer it – but could come up with a compromise, or even a scheme by which you could earn the difference in the form of a bonus on completion of certain projects, or by hitting targets within a specified time period. There are all sorts of creative ways in which employers can get around obstacles such as restrictive pay bands. Remember, there may be excellent reasons why your first choice can’t accommodate your salary demands – but these reasons won’t adversely affect the prospects, exposure, and training you would enjoy should you accept. Money isn’t everything.