There is no limitation on the number of names you can own, in fact many Companies and Organizations own quite a number of domain names and they have them all pointing to their main website. That means that a company that sells motorcycles for instance, and this is a purely hypothetical example, might have the domain name as the official website address and may also have the names "", "", "" etc. and thereby possibly increasing the traffic flow to their website. There's no reason why you or your company can't do the same thing and generate more and more traffic to your site. And this doesn't necessarily pertain to just "dot com". Many businesses have also registered or obtained pertinent names in other popular extensions like "dot net" and "dot biz  etc. again as a means of generating higher traffic flow.