Today I erased Macintosh HD and re-installed the OS (Catalina 10.15.7) in an attempt to start everything from scratch on my Macbook Air (Early 2014, pls don't judge me haha).

One of first things to do once the re-install was over was add a custom keyboard layout that I used to have and had backed up. I AirDropped the .bundle file and placed it in ~/Library/Keyboard Layouts, then opened up Keyboard Preferences, navigated to Others, and there were two of the same input source.

I headed back to ~/Library/Keyboard Layouts, removed the .bundle file, restared the laptop, then re-launched Keyboard Preferences and the custom input source was still there, only this time there was only just one.

It's really strange how a keyboard layout could have persisted a disk erasure + OS reinstall. Any ideas why this is happening or where the persistent keylayout file could be? This is making me a little bit paranoid tbh.