fix the two routes with the same path conflicts

[ivanoff]

Checklist

• [x] I have ensured my pull request is not behind the main or master branch of the original repository.
• [x] I have rebased all commits where necessary so that reviewing this pull request can be done without having to merge it first.
• [x] I have written a commit message that passes commitlint linting.
• [x] I have ensured that my code changes pass linting tests.
• [x] I have ensured that my code changes pass unit tests.
• [x] I have described my pull request and the reasons for code changes along with context if necessary.

[ivanoff]

fix of the following issue: https://github.com/koajs/router/issues/139

[etroynov]

@titanism @3imed-jaberi can you check it?