Can I send one email to create two different tickets in two Zendesk accounts?
No, currently it is not possible to send one email to create two different tickets in two Zendesk Accounts. Zendesk will create a ticket in the first Zendesk listed in the TO: line and will hard reject the email sent to the second Zendesk.
TO: support@Company1.zendesk.com, support@Company2.zendesk.com.
A ticket will only be created in the company1.zendesk.com Support account and will not be created in the company2.zendesk.com Support account.