Veneering over an existing dental crown is usually not a good idea
Veneering over an existing crown CAN be done, the bond is fine and should work, but normally the better choice is to replace the entire crown. It is usually done as a cost saving measure, but often in the long run there is no real savings if the crown eventually needs replacing anyway.
Veneers shouldnt be placed over another crown.
I have heard that some dentists try this technique but its highly frowned upon in dentistry. The best treatment is to replace the crown instead.