I did Taekwondo for many years, and so did my younger brother (he was better than me) and we would often spar.

I had lots of good level amateur boxing matches too, but would never spar with my brother, and wouldn't have ever fought him properly.

Proper boxing is a serious business, and the point is to hurt you opponent as quickly as possible. That's different from many other combat sports where the idea is to score points etc

I completely understand why two brothers would not want to have a professional boxing match between each other.

and I also agree with Lyle in that Vitali was a born FIGHTER whereas Wlad is the more talented BOXER, it's also something both Klitshkos have said in the past