Fix an obsolete option configuration values are duplicated when generating .rubocop_todo.yml

[ydah]

Create two files with the following code:

def fooBar; end

Set the following in .rubocop.yml:

Style/MethodName:
  IgnoredPatterns:
    - pattern1
    - pattern2

Run rubocop --auto-gen-config
Then duplicate configuration values are enumerated in .rubocop_todo.yml as follows:

# Offense count: 2
# Configuration parameters: EnforcedStyle, AllowedPatterns, IgnoredPatterns.
# SupportedStyles: snake_case, camelCase
# AllowedPatterns: pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2, pattern1, pattern2
Naming/MethodName:
  Exclude:
    - 'test1.rb'
    - 'test2.rb'

---

Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• [-] Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.

[koic]

Thanks!