Dose the sore a cause genital herpes and behet's disease look like the same? can the doctor diagnose them by eye ?

Bechets: Is a vasculitis that usually also involve oral mucosa. A careful history and direct observation may aid in distinguishing, although they can look similar sometimes.

Yes: The lesions of both conditions can look similar. Herpes is by far the most likely of the two. A dermatologist can help determine if behcet's is possible. So the answer to your last question is both yes and no. Behcet's is uncommon and can be a little more difficult to diagnose if your doctor has never seen it before.