You cannot use the same email address for a different account. You will need a separate email address.
You shouldn't have any trouble logging in ebay.com using your current account. Your account is universal across all ebay sites regardless of which one you originally registered on.
I registered on ebay.com and never had any problems logging in ebay.ca using the same account even when I was logged in ebay.com at the same time.
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Non payers should get unpaid item strikes and be added to block bidders lists. Period.