[SIS] has invalidated the vote ….saying it appeared that one of the members voted twice.
The inaccurate translations floating around on the web are far too many for this press release. The exact statement they issued was this: (Pardon the Swedish, but this needs to be done right, people are far too sloppy with translations. So, first I give the original two sentences stating the reason, then the English translation.)
SIS har information som pekar på att en av deltagarna i arbetsgruppen har deltagit i omröstningen med mer än en röst.
Ett sådant förfarande är inte förenligt med SIS regler som innebär att varje projektfinansiär endast har en röst.
A literal and careful translation of that would be: SIS has information indicating that one of the members of the working group has participated in the ballot with more than one vote. Such a procedure is not in accordance with SIS regulations, which state that each project sponsor has only one vote.
The wording is very carefully chosen not to point a finger to any particular member, and it does not actually say anywhere that "somebody voted twice". It says "somebody had more than one vote". It might be that two of the Microsoft representatives voted, that a company and its wholly-owned subsidiary both registered to vote, or it might actually be a case of SIS actually sticking out their neck and saying that many MS partners could not be regarded as independent voters. An interview with the SIS director has clearly stated that it was not a case of someone simply raising two hands for the count, or raising a hand for both sides, but that was all he wanted to say for now.
We simply can't tell from their press release exactly what the reason was, just that the Swedish vote was invalidated for reasons of procedure. If there is anything to be read between the lines, it would be that SIS used the vague count "more than one vote" instead of "two votes", but I would not read too much into that.
why and how SIS finds this out several days after the event
Reports from the meeting say that it was "chaotic", with far too many newcomers, some voters leaving the room, and heated discussions. To keep track of who voted what might not have been such an easy task. It might well have taken a day to sort this out, but I don't think they found out several days after the event that something was wrong, just that they needed a couple of days to decide how to handle this delicate issue. The vote was on Monday, the press release was published on Thursday. These people are standards professionals, they are used to working slowly and methodically, and to make sure things are done right. Haste is not right for standards work, as Microsoft and ECMA has found out lately. I think SIS got out of this honorably, given the ugly circumstances.