Blossom-Blessed Angel // Seed Suture

Being prepared isn't a copiable value. If a permanent becomes a copy of a prepared creature, it won't be prepared. That permanent will have the alternative characteristics, though, and some other effect could cause it to become prepared later.

A creature with a prepare spell can't become prepared more than once at the same time. For example, say Bloodline Recollector is on the battlefield and is prepared. During the current turn, three creatures die. At the beginning of the end step, Bloodline Recollector's last ability triggers. When that ability resolves, since Bloodline Recollector is already prepared, the ability won't cause it to become prepared a second time or create a second copy of Ancestral Craving in exile.

If an effect causes a creature to become unprepared, a prepared creature stops being prepared and the associated copy of its prepare spell in exile ceases to exist. If it wasn't prepared at that time, nothing happens.