I DON'T agree this demonstrates duality, so much as the illusory/delusory/hallucinatory nature of all our sense-derived experience. When we vest our energy appropriately, that transitory illusion we call reality nurtures our consciousness, when poorly done so, we "suffer"- but usually, suffering clouds our vision more than the positive emotions.
The "mug" is a "mug" not both a "mug" and "not-a-mug".
The "shape of a bear" is just that.
The "picture that appears" also (and illustratively much more transitory).
The coffee, the warmth, they appear as what they appear to be.
Welp, maybe the coffee is both coffee and salvation sometimes...
Hehe, some cold logic to counter Phils claims I like that :3. I agree with Phil tho: The mug can be empty or full, depending on it's state it is a completely different beast.
Just to darken the mood a little: Love and Passion are a gateway drug to hate, that does not make love and passion bad, but it goes to show that nothing is soley positive.