Are male Dobermans okay to raise together?

In general, yes. Young males need additional supervision though. Between the age of six months and two years, Dobermans are not mature enough to prevent their rough play from escalating into too rough of play, where injury is possible.

This supervision also applies when a young male, or female, is playing with other older dogs. A mature Doberman, especially a male, will play hardily with a young dog. If the young one escalates the mature one will not and may become injured.