Conflicting Allegiance

You are an expert in a special area in engineering, and are a paid consultant for two leading companies in your field. One company, slightly ahead of the other one you advise, has asked you to carry out the clinical testing of their product, but would like to cut down the costs of these trials by giving you a "gift" with the understanding that this money will be used for the trials. This allows them to avoid paying your university's usual fees for use of their lab space and equipment. What should you do? Includes discussion questions.