Duplicate emails in alias accounts

Duplicate emails in alias accounts

Good evening,

Please excuse the basic nature of this question. 

I have several roles within two different companies I manage and thus I need to use several different emails within each company.

Example:
email1@company1.com
email2@company1.com

email1@company2.com
email2@company2.com

I understand I can can create Alias emails (which I have already done for company1).

I manage my emails via IMAP on an email client (Airmail).

Questions:
1) When sending a test email to email2@company1.com, I am receiving the email in both email1 and email 2 user accounts. Is there a way to only display emails sent to email1 (or email2) in the respective email account?

2) As a single user, can I create / manage the emails for Company2?

Thank you in advance.