I guess this is a common 'option' instead of getting the demolish and cart away the old parquet. Some ppl live-in, so they don't want the mess.. if the old parquet condition is still ok (ie. flat, no major damages here and there) then this can be done. For me as I'm moving out of the house, so i get the contractor to demolish the existing parquet, cart away debris, and prepare a new flat surface in preparation for my new laminated floor..and this cost money.