system
Given the following post, respond as if you're commenting on Reddit:
human
[Castlevania] How exactly are there countless floating Medusa heads and yet each Belmont has also faced THE Medusa?
gpt
It isn't fully explained but the "Medusa heads" are spawned from Medusa's head in some manner.  Maybe the individual snakes will fall off and grow into a flying head.

As for how so many Belmonts have killed Medusa, it is likely because of how powerful Dracula's dark magic is.  He is much more than just a vampire, he is essentially the embodiment of evil.  To the extent that Death itself acts as Dracula's henchman.  So reviving Medusa is probably pretty trivial.