Render page with different content and template file names

I have a folder in my content, with content files named as ‘item.txt’.
In another folder, the content files are named as ‘item-collection.txt’.

Is it possible to use the ‘templates/item.php’ to render both kinds of pages?

Why do these pages use different blueprints if they are supposed to use the same template?

I want to conditionally show some fields in them, and the conditions depend on other things than a local field setting. For example I want to show the field ‘collection’ only if the parent page has the title ‘collection’.

It would be great if there was another solution instead of the different blueprints.

Depending on the conditions, a little hack would be to store something in a hidden field with a hook, at least that would work for the title of the parent and then make showing or hiding the collection field depending on that value. Might not work for all sorts of conditions.

As regards using the same template for different content file names, you could register the same template under different names in a plugin, I think.