Speaking more from a general knowledge of seal pushing in Japan, each organization will have a minumum number of authenticators on their board, equal to, or above which number, the article will be considered as having fulfilled the written testimony to the right. Naturally the less written there, the more likely it will achieve unaninimity.
Thus it might not matter whether you have four or six seals there as they simply attest to agreement with the top dog who will be the final arbitrator. Disagreement will cause a serious problem with their ability to work as a team, so in the unlikely event that there is an argument, they will have some inner mechanism to resolve the issue, usually by a further process of blanding, ie removing the offending word or phrase, or in extreme cases allowing the board member to offer his resignation.
Sorry for the long-winded reply, but you can see why once one judge has affixed his stamp, the others will fall into line; the actual numbers of seals means close to nothing, and all board members present on the day will have done his or her duty.