What are the differences between "dubious" and "incredulous", if any?

Cambridge Dictionary defines the words in the question as follows:

Dubious:

Definition: feeling doubt or not feeling certain

Examples:

1. These claims are dubious and not scientifically proven.

2. He has been associated with some dubious characters.

3. Ruth Ellis has the dubious (= bad) distinction of being the last woman to be hanged in Britain.

Incredulous:

Definition: not wanting or not able to believe something, and usually showing this

Example: A few incredulous spectators watched on as Paterson, ranked 23rd in the world, beat the champion.

Both words convey a sense of someone not inclined to believe something at face value, but really, are there any differences between these two words?