After update and the fix with IntergatedTunnels (crash server : issue #2083 ), we have all mob from nether into overworld.
Screenshots
https://i.imgur.com/m1VgDla.jpeg

Duplicate of #2078, I'm afraid there's nothing we can do about it, it shouldn't happen again in chunks you've been in with version 0.4.10 if that's any consolation ^^'

There's a possible sucky workaround btw:

Downgrade to 0.4.8, load a backup, add the mod Chocolate fix, visit all places you want not to change and then update to 0.4.10