What you're talking about is actually a definition of intelligence: being able to hold conflicting ideas whilst not adopting them. That is a psychological asset that is vital to skepticism and rationality. Where cognitive dissonance comes from is when a preexisting bias or belief is met with conflicting evidence, and an emotional discomfort appears.

Here's an example.

Imagine that you are someone who likes both cola and dark beer. You have a glass of cola on the table, but when you turn around someone switches it with dark beer. You turn back and take a sip of your drink, thinking it's cola (because they look the same), but it is actually dark beer. You will experience a moment of psychological discomfort, not because of the flavor of the drink (because in this scenario you actually like the flavor of both), but because