These are pretty close to being complementary. The closest I get using the Adobe Colour wheel is  #654FF0 and #F0DA4F - that's only one hex digit out for the green channel. 

[![enter image description here][1]][1]

The difference between F0DA4F and F0DB4F is imperceptible to the human eye. Might just be down to a rounding error somewhere, perhaps even a typo.

[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/YQhKj.png
  [2]: https://i.sstatic.net/46dKZ.png