The existence of one or more authorities incorporated under the provisions of this article shall not prevent the subsequent incorporation under this article of another authority or the amendment of the certificate of incorporation of another authority pursuant to determinations made by the same county or counties, even though the service area described in the certificate of incorporation, as originally filed or as amended, of any existing authority may include territory that lies within the proposed service area of an authority that is proposed to be incorporated under this article or that proposes to amend its certificate of incorporation under this article; provided, however, that the provisions of this section shall not be deemed to eliminate the requirements that the statements of fact referred to in subdivision (3) of subsection (a) of Section 11-88-3 and in subdivisions (1) and (2) of subsection (c) of Section 11-88-5 be determined to be true.