Section 153 of the Principal Act is amended by omitting subsection (1) and substituting the following subsections:

(1)  Mortgage duty is not chargeable in respect of that part of the amount secured by a collateral mortgage that is secured by –

(a) a mortgage or security instrument that is duly stamped under this Act or a corresponding Act; or

(b) a mortgage package that has been duly stamped under section 150 or a corresponding Act.

(1A)  A collateral mortgage that no longer secures the amount secured by a mortgage, security instrument or mortgage package mentioned in subsection (1) is not security for another advance unless mortgage duty for the amount of the other advance is paid.