Duplicity implies a bad quality, similar to lying or betraying someone's trust. She was hurt to discover the duplicity he employed to win the deal.
Pro Tip 2/3
Cautious Usage
Use 'duplicity' in situations when someone intentionally hides the truth. The politician's duplicity became apparent when his promises contradicted his actions.
Pro Tip 3/3
Not a Mistake
'Duplicity' is not the same as an honest mistake; it involves deliberate deceit. It was not a simple error; it was pure duplicity.