Why are there 2 Macintosh HDs in my storage? I reverted to mojave from catalina.
Why are there 2 Macintosh HDs in my storage? I reverted to mojave from catalina.
Without more details, it is likely the result from the Catalina installation. Catalina create a Macintosh HD - Data volume. If you didn't reformat the drive before reverting to Mojave, it is still there.
More info:
About the read-only system volume in macOS Catalina - Apple Support
WD