import re
 
regex = r'\[\[(([\w]+)::)?([^|\t\n\r\f\v]+)(\|([^\t\n\r\f\v]+))?\]\]'
print re.match(regex, '[[Home]]').group(2,3,5) # matches, good
print re.match(regex, '[[Home|Home page]]').group(2,3,5) # matches, good
print re.match(regex, '[[nw::Home]]').group(2,3,5) # matches, good
print re.match(regex, '[[nw::Home|Home page]]').group(2,3,5) # matches, good
print re.match(regex, '[[nw|Home|Home page]]').group(2,3,5) # doesn't match, good
print re.match(regex, '[[nw|Home::Home page]]').group(2,3,5) # matches, bad
print re.match(regex, '[[nw::Home::Home page]]').group(2,3,5) # matches, bad

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