Trying copy database to new URL for development but table names are not wp_

Please help.
I am trying to do a significant upgrade and theme change to my wordpress website.

I want to create a copy database on a test URL (ie https://www.mydomain.com and https://www.mytestdomain.com)

However I find that the original mysql wordpress database tables don’t start with wp_ but have a prefix of something else, eg ab_ (I presume at one point I considered a multi-site solution).

So my plan was to copy export teh original database and import it into the test URL. Then run “safe search and replace” tpo swap teh url’s over so that I could use them in the test environment – then put them back.

But the test environment cannot see the ab_ wordpress tables.

Please can anyone explain how I fix this.

Many thanks

Phil