ニコ: There have been arguements whether Gyokusho(玉将) or (王将) is correct at least since 17th century.

In diagrams in the books and magazines published by Nihon Shogi Renmei(Japan Shogi Association), 'Gyoku'(玉) is used for both colors.

On the other hand, if you buy a set of shogi pieces, there usually are one Gyokusho and one Ohsho as the Kings in it. It is a practice that a higher rated player uses the Ohsho and a lower rated player uses the Gyokusho in that case.

I think it will be no problem for Brainking to use two Gyokusho for both Kings.