Is the audience supposed to know that Palpatine is Sidious?

Knowing the context of the entire series, we know that Darth Sidious and Emperor Palpatine are the same person, but did Lucas intend for the connection/identity of the characters to be a mystery in the Prequels? If so, there should have been red herring characters so the audience would have to guess who really is Sidious behind the cloak instead of it obviously being Palpatine in disguise. Like maybe there could have been another politician character who is more vocal about his dislike for the Jedi to make audiences think that he might actually be Sidious and become the Emperor.

It’s kind of like too how there should have been more than one female love interest to keep the identity of Luke & Leia’s mother a mystery instead of it obviously being Padme.