User blog comment:B214/Question and Answers 2/@comment-24098614-20140425235909/@comment-1359322-20140426000510

Yes it's possible to have two Sacred Gears, Kiba has 2 and Saji has 4, of course they only gained the remaining Sacred Gears later. Whether a person can be born with 2 or more Sacred Gears is unknown at this point.

As to the second question, Sairaorg isn't really the possessor of a Sacred Gear, it's more like Sairaorg reincarnated a ownerless Longinus, thus becoming it's master/user than it's possessor. The Sacred Gear doesn't reside in his body after all.