Appending to title field

I wanted to add '(Complete Show)' to a bunch of my tracks so I used quick regex, selected title and:
Match: (.*)
Replace: \1 (Complete Show)

I always get 2 complete shows for some reason:

What's going on?

(.*) also matches the empty string, try (.+) instead.

An alternative would be to use Convert>Tag-Tag for TITLE
Format string: %title% (Complete Show)

What do you mean by matching an "empty string"? The whitespace? Some titles have more than one space character.

.+ does not work. The title remains unchanged.

Then please show us the regular expression in a screendump.

I just tried this:
which looks ok
does not.

Huh it worked today. Can someone explain why .* causes problems but .+ does not? Furthermore why does the appended word repeat twice regardless of how many words are in the original title.

I think this is the explanation. The * matches the previous token . (any character) between zero and unlimited times, as many times as possible. So it also matches zero times (in addition to one time) and produces an output for this case.