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Content can have multiple aliases in Drupal.

Additional aliases can't be created through the node submission form, though. You'll actually need to go into the URL Alias settings to do this.

Just follow the directions below:

Click on an image to make it bigger.
Pathauto - URL Path Pattern Configuration - List - Click Add Alias

1. Add a New Alias

From the URL Alias List at Admin Menu > Configuration > Search and Metadata > URL Aliases, click on the Add Alias button.

Pathauto - URL Path Pattern Configuration - List - Add Second Alias

2. Add Path

Path Alias field = enter a new relative path

Ensure your path is all lowercase, alpha-numeric and uses dashes to separate words versus spaces or underscores.

Click the Save button.

Pathauto - URL Path Pattern Configuration - List - Confirmation Alias Added

3. Updated Alias Confirmation

You'll be redirected back to the Alias List with a confirmation at the top of the screen.

Pathauto - URL Path Pattern Configuration - List - Test Alias

4. Test New Alias

In a new tab, test your alias out to make sure it works.