Little Ones #6 and #9

Just where did Little One #6 come from?
Lizzy mentions #5 in Mark of the Beast
Victor mentions #12 in Chapter 30 part 2, after he and Saul check the dead soldier.
Glenns says that #9 attacked Roman.

Pete mentions seeing #6 in Chapter 30 part 3, saying that is was seen earlier.

When Glenn recounts the tattooed numbers in chapter 31 part 1 he only mentions 5, 9, 12.

1) Did actor, Greg Miller, make a mistake and called #9 by the name of six?
2) Is #6 a Little One that was seen by Pete and Glenn, but not us?
3) Did Pete make an error by reading an upside down 9?
4) Was there a number on the one at the door in Chapter 30 part 2 or the one chasing them in Chapter 30 part 3?
5) Are the ones trying to smash the door and the one chasing them to the humvee the same Little One?