It means that the car that you have in your possession is not legally yours. You have a dash and title from a different car. Pay the $$ for Carfax.com and check out the VIN that is on the firewall.

For what it's worth, you may find out that the car you own is actually stolen. If you were to get pulled over and the police checked the VIN on the firewall, and found out that it didn't match, your car could get towed away.

Someone may have bought the car with no title, and took the title from a wrecked car, swapped dashes and registered the newly acquired one under false prentices.

Or someone welded on a new front clip, but I doubt that's the case here...

Bottom line, something's not right, you should find out why before you're blamed for something that you didn't do.