I can't speak for your specific area of IP but I am also pursueing an IP specialization. The IP lawyers I know only practice in their specific field of expertise and do not cross over into others. Also, in my school, I am required to take 15 IP classes + 1 externship, so technically, I can take classes in your field and my field, but more of less the externship will determine the field.
Also, most of the ones I know have taken and passed the patent bar, so they are both patent agents and IP lawyers.
It is not necessary but it would help you stand out in this very hot and growing field.