If you already have an account with your platform, you are not currently able to sign up for an account directly with Stripe with the same email. Instead, you can use an email alias (e.g., bob+stripe@example.com instead of bob@example.com) if you would like to sign up for an account with Stripe.

However, this rule does not apply in reverse: if you already have an account with Stripe, you can sign up for an account with your platform using the same email.