Scientists and researchers don't yet know whether infection from this latest strain of Coronavirus induces immunity, or in fact if any acquired immunity can provide ongoing protection from Coronavirus.
Previous studies (like one done in an issue of Emerging Infectious Diseases in 2007) found that for SARS-CoV2, human antibodies to the virus remained at consistent levels for roughly two years, and then fell off. There aren't many studies about simultaneous infection by multiple strains of Coronavirus, likely due to spread pattern occurring independently. It's certainly possible to be infected by more than one virus simultaneously.
The big takeaway from this is that viruses are competing for limited resources (you and me), and may not like to share. If you were subject to multiple viral infections, it's tough to say whether or not you'd be better off as a result of that competition, but probably not.