It matters, in the same way intent matters when you cut somebody with a blade. Was it attempted murder? Self-defense? Carelessness? Accident? Surgery?

Lies, similarly, are fundamentally destructive - a lie is a piece of invalid data that corrupts, to smaller or greater extent, the minds of everyone who come in contact with it. Incorporating a lie in your reasoning moves you further from accurately perceiving reality. Sometimes, very rarely, a lie may be justified - the best of available options, even accounting for second-order effects. Usually, it isn't. But it matters whether the lie was accidental, good-faith, attempt at poisoning someone's mind, or wanton disregard for peoples' ability to grasp reality.