[Abagail]

Attached player objects aren't treated as SA-MP or per player objects, it's a totally different method. Some scripters vary on how they manage indexes, some use the next available one and some use predefined indexes for different objects.

Refer to:
https://sampwiki.blast.hk/wiki/SetPlayerAttachedObject
https://sampwiki.blast.hk/wiki/RemovePlayerAttachedObject
https://sampwiki.blast.hk/wiki/IsPlayer...ObjectSlotUsed