Are base runners always protected on a illegal pitch?

[derwil]

Originally Posted by robbie

#3 Coach MAY or MAY NOT have an option. "If the illegal pitch is hit and all runners including the batter-runner , advance one base, the play stands."
* This could lead to a situation where, for example, the D could get a double play and the O would have to live with it. - Is this different in other rule sets?

Not sure how you have a double play and all runners advancing at the same time. If the runners are out, then they did not advance......Maybe runners advance then double tag out at third and second?? Uck..ugly play but I guess possible.