EDITED original post for clarity. (15 October 12:45am)
This is working for me using your two examples, the regex may need refining if it throws up false positives in your library.
To find files with trailing duration suffixes, create a Smartlist, name it something meaningful then use Import/Export and paste the following into the Smartlist rules data window:
[Media Type]=[Audio] [=Regex([Name],/#(\s\(?\-?\s?\d+:\d+\)?)$#/,0)]=1
To 'clean' already imported files paste the following into the Name tag in the Tag Window:
=Replace([Name],Regex([Name],/#(\s\(?\-?\s?\d+:\d+\)?)$#/,1),)
To 'clean' files as they are imported use auto-import as described in this post here:
https://yabb.jriver.com/interact/index.php/topic,130173.msg907787.html#msg907787BUT paste the following into Value field:
Replace([Name],Regex([Name],/#(\s\(?\-?\s?\d+:\d+\)?)$#/,1),)
EDIT: Superseded (with breathtaking speed) by in-built MC functions - see Matt's post below.