creating an amplified world corrupts future "default" terrain generation

i created an amplified world for fun, and got bored of it. deleted it and created a new default world. i spawned into a pseudo-amplified world, with giant mountains and floating islands as well as biome and terrain generation corruptions ex [ mountains being cut in half or biomes having a straight visible chunk border with land formations cut off.

What I expected to happen was...:
the default terrain generation shouldnt be affected by anything but the options i selected, but this happens regaurdless of if i choose default or amplified

What actually happened was...:
upon creating a default world i was spawned into a corrupted overworld with terrain generation from both amplified and default

Steps to Reproduce:
1. delete all current worlds
2. create an amplified survival map and delete it
3. delete amp world and create a new default