Analysis of information sources in references of the Wikipedia article "구루 고빈드 싱" in Korean language version.
Gobind Das was the original name of the Tenth Guru, at least so it seems. Muslim sources generally refer to him as Gobind Rai, but documents issued by his father, Guru Tegh Bahadur, give his name as Gobind Das.
Guru Gobind Singh's name was Gobind Das or sometimes said to be Gobind Rai, but from the founding of the Khalsa he is known to be Guru Gobind Singh.