CTA focus for Sign up or Sign in?

In my web registration form I have signup/signin button options (CTAs).

I do not want to confuse the user with two bright and obvious CTA buttons, myself and my client would much rather have just one of the buttons have more focus.

But we do not know which would be best for our situation. Is there a general rule for this?

For example: Register as new user: enter image description here

Or

Sign in as existing:

enter image description here

As you can see the blue filled CTA is supposed to have more focus than the inverse.

Edit: the "new user registration" form is quite lengthy, it has a minimum of 6 fields there are more fields depending on how the user answers. So I would like to separate these two options onto one single page without the input fields.

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