That in the event the board of any of the institutions aforesaid should find it advisable to issue bonds under this act N.M. Stat. Ann. § 6-13-1 to 6-13-26 in more than one series, or at different times, for any of the purposes aforesaid, then each series of said bonds shall be designated by the letter “A,” “B” or in some other designation to the end that each series shall be kept separate, and all of the requirements of this act shall apply to and be faithfully followed, done and carried out as to each of said series.