Which Sutta? Karma of unknowingly doing evil is worse than knowingly doing evil
The following sutta is not about kamma (but is about internal defilements). 


  Mendicants, these four people are found in the world. What four? One
  person with a blemish (aṅgaṇa) doesn’t truly understand: ‘There is a blemish in
  me.’ But another person with a blemish does truly understand: ‘There
  is a blemish in me.’ One person without a blemish doesn’t truly
  understand: ‘There is no blemish in me.’ But another person without a
  blemish does truly understand: ‘There is no blemish in me.’ In this
  case, of the two persons with a blemish, the one who doesn’t
  understand is said to be worse, while the one who does understand is
  better. And of the two persons without a blemish, the one who doesn’t
  understand is said to be worse, while the one who does understand is
  better.
  
  MN 5


I cannot imagine knowingly doing evil wicked kamma is better than not knowingly doing evil wicked kamma (such as the wicked Mara kamma of reviling Noble Ones &amp; making false declarations of jhana attainment). Knowingly doing evil wicked kamma sounds psychopathic.