There are two prominent persons with this name. First, one of the hundred kouravas. Second, son of Karna. The kourava Vikarna was killed in the war by Bheema on the seventeenth day of the war. Vikarna opposed his eldest brother Duryodhana and Karna in the court hall when they called Droupadi a "slave" won in the dice game. He argued that Yudhishthir had no right to stake the Paandavas' common wife , after losing himself first in the game, thus losing his own right on her. But, his voice was cornered by the dominating side. All the elders and neutrals admired his sincerity towards dharma. Thus he looked an odd man out in the kouravas lot.
Another person with this name was one among Karna's sons. He was killed in the war by Arjuna.
In viraata-parva, on the occassion of northern cow-seize , Vikarna attacked Arjuna and was defeated. It was not sure which one he was. But the sequence of the fighters suggests thst it might be Karna's son as the next attackers were Karna's brother and Karna in that order.
It is quite common in this great epc that many persons occur with the same name. We should be careful in identifyibg them.