Dear jamie.tse,
Good day!
Thank you for posting to Microsoft Community. We are glad to assist.
As per your mentioned description about "Outlook Rules: same keywords". Depending on how many rules you have, the top rule with similar conditions in Outlook takes priority.

For instance, as an example, I created a with name sam and condition for emails with "subject title keyword "Sam" to move to folder "family" while the rule named john to move emails with "subject title keyword "John" to folder "business". As per the result, if subject title appears to be "Sam & John celebration, it will apply the "John" rule to move email to the business folder because it is the top (priority) rule in my outlook email rules list as it shown on above screenshot and it has the same condition with the next rule "Sam".
For more info about how to Manage email messages by using rule kindly refer to Manage email messages by using rules - Microsoft Support
I hope the above information will be helpful. Please feel free to let me know if there are any updates or if I've got you wrong. I will keep assisting you based on the information you provide. We sincerely appreciate your patience and cooperation.
Thanks for your precious time.
Have a nice day!
Best regards,
Inema | Microsoft Community Moderator