When was Dai Suu Shii changed to Two Yakuman?

[Goldeneye]

Prior to Sloper's Shanghai Dynasty, I always remembered that Dai Suu Shii was awarded One Yakuman - the original Yakuman GB game gave it just One Yakuman.

I wonder when that got changed so that it gets awarded Two Yakuman? (Or more in general when multiple Yakuman was started to be established)

[Shirluban]

It's a not recent and that's not for everyone.

Depending on the local rule, some people count Dai Suu Shii as one yakuman, others count it as two yakuman.

[Tom Sloper]

Prior to Sloper's Shanghai Dynasty, I always remembered that Dai Suu Shii was awarded One Yakuman - the original Yakuman GB game gave it just One Yakuman.
I wonder when that got changed so that it gets awarded Two Yakuman? (Or more in general when multiple Yakuman was started to be established)

That game was released in 1997. I was learning Japanese rules from Little Tokyo (Los Angeles) players in 1996. I collected computer mahjong rules from Japan and provided them to my teachers. The double yakuman choice was one of several decisions my teachers had to make when they recommended what rules and options I use in Shanghai Dynasty at that time.
The rules we used in that game were never made "biblical" throughout the riichi mahjong world -- that is to say, we were not dictating, we were only reflecting. And we were only reflecting a part of the riichi mahjong landscape that was visible to us at the time.