Jockey mobs spawn seperated (probably dupe, couldn't find it)

Ever since 1.12 I noticed chickens in the Nether and in caves. After a while I started seeing Chicken Jockeys spawn seperated. It happened just a few minutes ago so I decided to post it here. On the pic you can see the chicken is indeed a jockey, however it spawned a minute or so ago without a rider a few blocks away from me.