I feel like the amount of control you have over other people's tadpoles, along with several story beats, make it pretty clear the player character and party's tadpoles are not normal. It's also clear that these things aren't operation on auto pilot, someone is pulling the strings. I can totally see this person/deity/whatever just leaving the tadpole in your party because they know you're probably going to revive them at some point. You can't cast revivify on anyone other than party members anyway, so if we're conflating gameplay and story elements, that alone shows there is something special about them.
