Is a naive immune system equally able to handle new antigens as an educated one?
They will both go through a primary and secondary immune response. So first low affinity antibodies will bind, the corresponding b cells will undergo affinity maturation, somatic hypermutation until high affinity (perfectly fitting) antibodies are available and these antibodies will finally undergo class switching.

Depending on the antigen an innate immune response will also be triggered as part of the first line of defense. There is no difference in the immune response between these two hypothetical brothers.