Notion of good and bad in Buddhism
The original Buddhist teachings do not include a doctrine of non-duality. The Buddha's enlightenment came from ending craving &amp; attachment rather than from ending dualistic perceptions &amp; thoughts.

Understanding good &amp; bad for moral/social purposes is one kind of knowledge. 

Seeing &amp; understanding the true nature of reality for liberation is another kind of knowledge. 

The Buddha taught: (1) avoid evil; (2) do good; &amp; (3) purify the mind. Purifying the mind means ending egotistic attachment towards good &amp; bad rather than giving up the understanding of good &amp; bad.


  'See evil as evil.' This is the first Dhamma discourse. 'Having seen evil as evil, become disenchanted there, dispassionate there,
  released.' This is the second Dhamma discourse. These are the two
  Dhamma discourses that the Tathagata — worthy &amp; rightly self-awakened
  — has given in sequence.
  
  Itivuttaka 39