If I follow what you're saying, then yes it's possible that total toe wouldn't change (one side toes out, the other toes in) but there would be some side effect. For example, if the vehicle goes straight, the steering wheel would rotate one way or the other, conversely, if the steering wheel doesn't rotate, the car will change direction.

This is often seen on lifted straight axle trucks. More often on one's with push pull drag links that don't follow the spring arc.

Toe changes that would be less noticeable would be if both wheels toe in or out equal amounts. The car would still go straight and the steering wheel wouldn't rotate. This would be noticeable however on roads with uneven traction. Say a patch of ice on an otherwise dry road. The tire with better grip will steer the car as the other slips.