Delete duplicated words.

[smstong]

Delete duplicated words.

Is this a quick PR -- Typo, Quick Wording Fix, etc? If so, you don't need to follow the template -- please delete all and make the title of the PR representative of the changes and add a member of staff to review the PR. Thank you so much!

Description

Replace this paragraph with a description of what this PR is doing. If you're modifying existing behavior, describe the existing behavior, how this PR is changing it, and what motivated the change.

Related Issues

Replace this paragraph with a list of issues related to this PR from the issue database. Indicate, which of these issues are resolved or fixed by this PR.

Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes ([x]). This will ensure a smooth and quick review process.

• [ ] I updated AUTHORS with my name and email.
• [ ] I read the Contributor Guide and followed the process outlined there for submitting PRs.
• [ ] My PR builds for all changed/updated/fixed behaviors (See [Contributor Guide]).
• [ ] I updated/added relevant documentation.
• [ ] The title of the PR is descriptive and doesn't have [WIP]
• [ ] I updated CHANGELOG.md to add a description of the change.
• [ ] I am willing to follow-up on review comments in a timely manner.

Breaking Change

Does this cause any new material not previously covered in the course to be required?

• [ ] Yes, this is a breaking change (please indicate a breaking change in CHANGELOG.md).
• [x] No, this is not a breaking change.