re = /^[A-zÀ-ÿ ]*\1*,(?:\s)(\w*,\s)(CEP (\d{5}-\d{3}))/im
str = 'Rua das Flores, 123, CEP 60321-105
Avenida Brasil, 456A, CEP 16945-017
Travessa dos Santos, 101, CEP 12345-678
Rua Catarina, 243, CEP 25437-987
Rua Sâo Pedro, 243, cep 25437-987
'
subst = '\\^[A-Za-z ]*\\1*,(?:\\s)(\\w*,\\s)(CEP (\\d{5}-\\d{3}))\\'
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html