If you need more heat, or just want to make your firepit look more impressive than your neighbors, then why not install two burners, instead of one.
Note: Each burner has it’s own control box and operates independently. If you intend to use natural mains gas, you must check with your gas engineer to ensure you have enough spare capacity from your meter, before finalizing your design. If you don’t he won’t install them.
For LPG bottled gas, you can have as many burners as you like, as each runs from it’s own gas bottle.