When does the game determine which fossils are which? When they are "buried" at 5am? When I dig them up? Or when Blathers assesses them?
For example, if I dig up a fossil, does the game already know that it is a Diplo Skull, or is that determination not made until I hand it to Blathers?
Consider this scenario:
Let's say there is a rule that each day's new fossils are distinct. (Is there such a rule? That would be another question.)
I dig up my four and take one to Blathers. He tells me it's a Diplo Skull. Now I send the other 3 to my friend on another island. ... Can I be sure that none of the remaining three are Diplo Skulls? ... or will her Blathers decide based on her island's state?