Help! Throttling disk IO while trying to rid duplicates within "open with"

Help, please.

In an attempt to rid my "open with" list of duplicate entries, ran:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchSe rvices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user

In response, Terminal output, "throttling disk IO." Oy! Sounds ominous. And the duplicates in "open with" remain. Lose, lose.

What have I done to my system? More importantly, how do I undo it? And is there a safe way to rid the duplicates.

On my older system, have run (what I believe to be) the same line, which did clear duplicate entries.

Thanks!