Perceived object X can be distorted to n degree, such that recognition is impossible. Or X can be entirely replaced with another object Y, that mimics the n degree, but also the way it’s distorted m. The effect is the same, though a bit of knowledge can be gleaned from the former case. If distortion is present, an actor could be aware of the deception. In an entire replacement of X, the actor may be oblivious; it’s just another strange thing passing through perception.
This distinction implies another actor—the deceiver—to be involved. Normal folks wouldn’t be suspect of foul play unless they know someone is behind it all, unless abstractly through personified circumstance: i.e., “The fog really had it in for me that day. I almost got in the wrong car!”
As always, there’s plenty of wiggle room. See the Eubulides’ Elektra Paradox (there’s virtually no better Google search result for it).