It would be very unusual for them to grow “extra” teeth. If anything, Toy dogs have missing teeth.
What happens, is that sometimes Havanese (and other toy breeds have retained baby (deciduous) teeth. USUALLY these teeth fall out by 7 or 8 months. But you need to keep an eye on them, because if they do not, they can make the puppy’s bite go off and cause problems with their adult teeth. So if you are not sure, make sure you have the vet check for you!