Word-for-word from @Kaartic at https://www.mediawiki.org/wiki/Topic:Tpjny7yhimc6iiph :

When trying to edit parameters that already exist, the template description editor, must warn the editor in case any other parameter with new name already exists. Instead it seems to append numbers to the name which could go unnoticed.

Steps to reproduce

• Go to Template:Em page
• Edit the page and invoke the Template documentation editor using Manage TemplateData
• Edit a template parameter which has the name title and change it's name to style

Expected results
Warning is displayed to the user about an already existing parameter with the same name.

Actual results
An integer is appended to the new name (e.g. style0). It could go unnoticed to the editor.