It is an encoding problem, to solve it, I suggest:

1. Encode the file to ANSI. The character \xB7 is now displayed ·
2. Do the replace via Replace toolbox. Find: \xB7, Replace: what you want
3. Encode to UTF-8

BBEdit is a really great Mac text editor, and can show invisible characters. http://www.barebones.com

• Ctrl+F
• Find what: ^.*(\(.+?\))\h+\1.*$
• CHECK Wrap around
• CHECK Regular expression
• UNCHECK . matches newline
• Find All in Current Document

Explanation:

^           # beginning of line
    .*          # 0 or more any character but newline
    (           # start group 1
        \(          # openning parens, have to be escaped
        .+?         # 1 or more any character but newline, not greedy
        \)          # closing parens
    )           # end group 1
    \h+         # 1 or more horizontal spaces
    \1          # backreference to group 1 (i.e. the same value)
    .*          # 0 or more any character but newline
$           # end of line

Screenshot:

Yes, it does. The way to enable this depends on your version of Notepad++. On newer versions you can use:

Menu View → Show Symbol → *Show All Characters`

or

Menu View → Show Symbol → Show White Space and TAB

(Thanks to bers' comment and bkaid's answers below for these updated locations.)

On older versions you can look for:

Menu View → Show all characters

or

Menu View → Show White Space and TAB