Hello.
I don't understand why you needed to clone the template, if you can create or duplicate unlimited template styles.
The answer about using 2 different blog styles in each template is not important, the important thing is the MENU ITEM, if for example your element is blog in one and in the other it is blogpremium, you only have to select a new style in your menu element, but if this element is unique for both (blog) the solution would be to edit ublog.php of your cloned template and instead of waiting for the configuration of the menu element you pass it the name of the style, in this way the style you want will be loaded arbitrarily without respecting the configuration of the menu element (of course only the style, the rest will continue to be obtained from the configuration of the menu element).
Greetings