The United States Mint had issued a 9/11 coin scam warning following a product by National Collector's Mint; "10th Anniversary September 11th Commemorative Dollar" and claims that it is a "Liberian government authorized legal tender coin." US Mint warned users that this product is not a genuine United States coin or medal. Under the Constitution, Congress has the exclusive power to coin money of the United States. Congress has delegated its authority to mint and issue coins to the Secretary of Treasury, and Congress requires the Secretary to carry out these duties at the United States Mint. Thus, the United States Mint is the only government entity in the United States with the authority to coin money.
Consumers may find the advertisements for this product confusing because the National Collector's Mint uses phrases such as "legal tender dollar." The product itself may be confusing because it bears the denomination "One Dollar." Congress did not authorize the National Collector's Mint product, and the United States Government does not endorse it. On January 2011, US Authority said they're investigating a Fake September 11 coin minted by the National Collector's Mint. Two Democratic New York congressmen, Rep. Jerrold Nadler and Sen. Charles Schumer, have accused the National Collector's Mint in Port Chester, New York, of selling bogus September 11 coins in an attempt to exploit the tragedy for profit.
The only official United States coin or medal to commemorate the 10th anniversary of the September 11th attacks is the "National September 11 Memorial & Museum Commemorative Medal," which is authorized by Public Law 111-221 (approved by the President on August 6, 2010). You can read the scam warning in US Mint website; 10th Anniversary September 11th Commemorative Dollar Alerts. I also found some news video by WPRI TV relating to that matter:
