Unfortunately, trade names are not exclusive in Colorado. Multiple persons or entities can use the same trade name and often do. Trademarks, on the other hand, are something to which an owner can claim an exclusive right. It isn't uncommon for a business to have a trademark and trade name that are identical, but a trade name isn't necessarily a trademark (vice versa). Even if you have not registered a trademark with the State of Colorado or the U.S. Patent & Trademark Office, you could still have common law trademark rights. You should really discuss this with an Intellectual Property attorney to assess your rights. I also encourage you to consider doing business through an LLC or corporation. If done and maintained properly, individual owners of such entities are not personally liable, in general, for claims against the business.
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The key question is how you are using NSR. If it is simply a name of the company (dba) then it does not really matter. If, however, you are using the name as a service mark, i.e. you advertise NSR for remodeling services, you probably have common-law rights in the name. One problem with common law rights is that they can be limited geographically. You really need to sit down with a trademark attorney and provide them with 1) samples of your advertising and 2) an idea of what geographic area you have served over the last 5 years. He or she will then be able to give you a better idea on how to proceed against the newcomer.
This is not legal advice. Even if it were, fee legal advice is worth what you pay for it. The facts of every case are different and should be addressed by a competent attorney who has all of the facts.