Problem creating & accessing an additional product template

I am interested in creating a new product template for experimentation with slightly different features than the original without disrupting or eliminating the current product template. I tried to simply clone and rename the product.tpl to somethingelse.tpl and I received a page not found error when I put the newly renamed page in the url (presumably in the correct format). I see multiple instances of product.tpl and product.php in a variety of folders; Is there any documentation about how all these scripts and templates are related?

Additionally, it would help to understand how the url works and if I need to create additional files and directories to add/clone the category or product templates? Also I see php files in the system/engine directories with parsing and concatenation functions, presumably for the url. Are the page or template names maintained in an array or in the database somewhere? Do new templates need to be added to the database or enabled in the Admin panel like the tutorial I saw on modules? Any link to more comprehensive documentation would be great.

I read the light documentation on folder structure and the MVC architecture. If anyone has more details on the way these pages/scripts interact, I would prefer to do my development in keeping with the architecture.

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Thank you.