Not only do people do this, it's actually extremely common, ask anyone with commonname@gmail.com. Someone here said their original email address has become unusable because it gets thousands of messages a day that are intended for other people. "That guy" might actually be multiple people all making the same mistake with your email address.
My coworker told me there's a complete stranger who, every time she emails her son, accidentally sends the email to him first. This has been going on for years, she makes the same mistake every time, she doesn't learn her son's actual email address, and she doesn't learn to press "reply."
I'm 100% sure the "non-dot-version" doesn't exist as a separate account.
AOL used to allow users to email other users without using the @aol.com extension. Back in those days I (prior to any capacity to negotiate a sensible ISP, for the record) had an email that matched a common subject line that was inundated by people who typed their subject in the To line and then wrote an email.
