Trademark law as applicable here:
Trademarks that are descriptive and have achieved distinction through sales and advertising can be protected under federal and state law.
One trademark legally conflicts with another when the use of both trademarks is likely to confuse customers about the products or services, or their source.
In case of a legal conflict with a later user, the first commercial user of a trademark owns it.
If a legal conflict is found to exist, the later user will probably have to stop using the mark and may even have to pay the trademark owner damages.