You'd better confirm with them before you go

to make sure that they really haven't dismissed your application.

I don't think the recruiter will do anything bad to your application, they just wanted to make sure the company you are applying is not same as theirs, nothing to worry about.

As for dress code, if they said it's ok to dress casual, then don't need to dress formally. In my career, i never dressed formally to interviews, the reason is that if u dress formally, they may think u r begging them for the position. Just my feeling.