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I thought you were going off a new installation, sorry. You said new client, so I Assumed new installation. You could try a different table prefix, but you could also export your tables (with drop_tables) and download your current DB.
Install in a NEW directory, with a new DB. Once you have it up and running, import the tables you just exported, edit your mainfile.php and you should be alright.
So long as you can create a NEW DB, then you don't have to make a new table prefix.
Treat it like a migration by installing in a new Dir, getting it running and moving your tables from the old into the new and then copying your files over. Adjusting the mainfile.php will be the final step and you should be good to go.
I know I repeated myself, I'm having a hard time explaining myself tonight. Hope you follow my drift.