Nothing contained in this subchapter shall prevent the issuance of additional bonds, from time to time, if the bonds shall be authorized by law. However, all such additional bonds shall be subordinate to bonds issued pursuant to §§ 14-235-215 — 14-235-217 in respect to the application of revenues to such additional bonds unless the additional bonds consist of revenue bonds issued under this subchapter, the issuance of which was expressly authorized in the ordinance or indenture governing prior bonds of similar character. In this event, the additional bonds and such prior bonds will have a parity of lien unless the governing ordinance or indenture shall provide to the contrary.