Each member of the board of registrars shall receive sixty dollars ($60) per day, for each day’s attendance upon the special sessions of the board required under this article; but if such special session is held on the same day a regular session is required to be held under the laws of this state, registrars shall receive only one per diem allowed for performing their regular duties, it being the intent and purpose of this article that registrars shall be entitled to receive only one per diem allowance for one day’s service.