Sending an email to multiple aliases at once

[moaazassali]

I have two aliases a@alias.com and b@alias.com that forward to a@domain.com and b@domain.com, respectively.
When I send an email to both a@alias.com and b@alias.com at once within the same email, the email only gets forwarded to a@domain.com. Meanwhile, b@domain.com receives nothing.

I have attached an image below which shows the log for the issue and how it only forwards it to a single email (usually the first email listed)