(Author Date) inline citations vs anonymous references with ISO 690
ISO 690 is rather unambiguous about this (section 5.6. "Anonymous works"):


  For  anonymous  works  cited  by  the  name  and  date  system  (see 
  A.2),  “Anon”  may  be  used  instead  of  a creator's name. For
  anonymous works cited by the numeric system (see A.3) or running notes
  (see A.4), the title may be treated as the first element. If the
  creator's name is known, it may be supplied.


If your publication venue requires you to use ISO 690 with name-date, you really don't have any choice here. After all, consistency is why journals etc. require you to follow a citation/publication style.



As per appendix A.2, you can distinguish different anonymous works from the same year by appending letters: (Anon., 2016a) vs. (Anon., 2016b). This is standard in Harvard style derivatives.