Yes, they are unique coasters. Some people really do travel that much and ride that many coasters.
However, exactly what people count as a new coaster credit varies from person to person. Some people count powered roller coasters (like Alton's mine train or Thorpe's Flying Fish), some don't. Some people count relocated roller coasters (such as the old Traumatizer from Southport which was moved to Blackpool and renamed Infusion) as separate credits, some people don't. Some people count the two identical sides of racing roller coasters (such as Rebel Yell at Kings Dominion or Gemini at Cedar Point) as two separate credits. Everybody has their own way of counting coasters, so bear in mind that you're not always comparing like for like.