fix: client duplicate function now allows db param to be passed

[markmcnelis]

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• Does npm test pass with this change (including linting)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?

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Description of change

When invoking the redis client duplicate function the new client will respect a new selected_db target if the db option param is passed.

Thoughts?

fixes #1281

[BridgeAR]

Thanks a lot for your contribution!