As any self-respecting SEO does, I make an effort to canonicalise all URLs that I deal with. As a preference, this is always with a server-side redirect, with a 301 status code. This applies to both individual files and also to entire domains.
For instance, Receptional owns a number of TLDs other than .com which map to this website.
Historically, when you search for a non-canonical URL that redirects, Google will instead display the canonical URL. You can double-check that URLs are correctly mapped to the correct location using the id: search operator:
I noticed today that if you search for a non-canonical domain as a keyword, Google displays that URL in SERPs - not the place that the URL actually arrives at via a redirect. For instance, when searching for [receptional.net]:
I wonder why the second example includes a www, but the first doesn't. In any case, I imagine that Google are doing this because it doesn't want users to believe that the absence of the exact domain they searched for means that the site is not available. Most likely, this increase the clickthrough rate of the listings.
Still, it's interesting that the URL displayed in SERPs will not match the destination in these cases. I'm sure there are some cases where this could be undesirable!