[jquery]

Convergent evolution. It’s probably just an amazing and fortuitous coincidence. They look similar but have completely different internal structure, like a bug that pretends to be a leaf. I can’t go any further without spoilers, so I won’t.

[debugnik]

There might be a slim evolutionary thread between them, actually. DDLC made a reference to a certain Gravity Falls episode which has a similar premise by releasing exactly 3 years later, and that one could have been inspired by the then recent release of Totono during production.

But I agree it's convergence for the most part, it's not that hard to come up with that premise even if it hasn't been too common.