The database has Dust RoboRider as 8512 and Onyx as 8513, where in fact they are the other way around. If you follow the links below to the official Lego RoboRiders site you will see the correct part numbers. Onyx 8512 - (URL) 8513 - (URL) (24 years ago, 28-Nov-00, to lugnet.admin.database)
(...) Thanks, Martin. Since I've never seen an error in the database, I was sure *I* was the one who was mistaken about the set number of the two Onyx sets I bought today. (24 years ago, 5-Dec-00, to lugnet.admin.database)