Section 3. In consideration of the franchise and rights hereby granted, the grantee shall pay into the treasury of the Philippines a franchise tax equal to two per centum of the gross earnings for electric current sold under this franchise. Provision of laws to the contrary notwithstanding, the franchise tax equal to two per centum of the gross earnings of the grantee as provided for in the original franchise granted by the Municipality of Marikina, Province of Rizal, shall be respected. Effective upon the date the original franchise was granted, no other tax upon its capital stock, franchise, right of way, earnings and all other property owned or operated by the grantee under this concession of franchise shall be levied or assessed on the herein grantee except the franchise tax of two per centum of the gross earnings mentioned in the said original franchise.