Does placing more than one in the same barn or coop help with achieving animal friendship faster?
Edit: apparently not (Thanks Ereo)
No, the autopetter effect is a 'checkbox' so-to-speak, just being yes there is an autopetter or no there is not and not having any different outcome based on multiple or different location, etc.
My understanding is that AutoPetters maintain, but do not improve friendship and don't do anything for mood.
No, the autopetter fulfills the petting check (nullifying any potential loss from not petting), and also gives friendship, though half that or normal petting (8 of the manual petting 15). It also gives the
full mood as regular petting (32 or 36 mood depending on animal if I recall correctly)