What's this?

I don't understand what this means (Duplicate arguments in template calls) so can someone explain a little? Thanks
Dominic305.png Dominic305  Talk  Contribs  Scratch 
13:08, 2 May 2019 (UTC)

If someone uses a template like this:
|argument=another value
(or in general specifies the same argument twice) it's idiotic and doesn't work and pages that do that go in this category.
Kenny2scratch logo.jpg kenny2scratch  Talk  Contribs  Directory 
13:09, 2 May 2019 (UTC)