Jennifer Green, MD and Bruce Leslie, MD recently published an article in the Journal of Hand Surgery describing the incidence of bilateral distal biceps tendon ruptures at the elbow. After looking at their experiences with 321 patients with this injury (to this date, the largest single series in the world), the authors found that 8% of all patients with a distal biceps tendon rupture will have the same injury occur in the other elbow at some time in their future.
A link to the article is here.