If you already have an Express account, you will not be able to sign up for a Standard (Stripe.com) account with the same email address at present. As an alternative, 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 a Standard account.
However, this rule does not apply in reverse: If you already have a Standard account, you can sign up for an Express account using the same email address.
Some helpful tips:
A user with an existing Express account may use the same email address to sign up for an Express account with another platform as long as the phone number also matches. If you encounter an error message stating, "An account exists with this email address but with a different phone number. Please use a different email address or enter the phone number ending in...", this may be due to a mismatch in the email address and phone number used across the multiple Express accounts. For more information about this, please take a look at this article: I've lost my phone or changed my number – how can I log in to my account?
If you sign up for a new Express account with an existing email address (either Standard or Express), your bank/debit card details will be copied over to the new account. Once your account is fully operational, editing the payout details will not affect other accounts linked to the same email address.