 Two runners one base is never a good situation at least for the offense. It's actually pretty nice for the defense One of the runners is going to be out But it depends on the situation as to which one if the leading runner on the play has a force out at the next base Then he is going to be the one who gets called out whenever he is tagged So let's say their runners on first and second base and there's a ground ball hit to the shortstop right in front of the Runner who started on second base Thinking he's probably going to get tagged out the runner just decides to turn back around and go back to second base Ignoring good fundamentals in his third base coach who's probably losing his mind about now While that was happening the runner on first base like he should have has run to second base Seeing that there are now two players on second base The shortstop's probably just going to walk over and tag both of them which is important But we'll come back to that in a second So because the runner who started on second base is the leading runner in this situation And he has that force out at third base He will be the one called out and the runner who started on first is entitled to second so he will be safe Alternatively the shortstop could have simply gotten the force out at third base and again the runner who started at second would be out On the other hand if there is no force out for that leading runner then the trailing runner will be out So let's say we have a second scenario But the same situation again runners on first and second this time though The pitcher turns around to make a pickoff attempt at second base There's some kind of run down that's too complicated animate and PowerPoint and the runner gets back to second base But amidst that chaos the runner from first has run to second base and now both runners end up again on the same base Our shortstop again tags both runners, but this time the umpire should call out the trailing runner That is the one who started on first base Why is this different in this situation that lead runner is not forced to third because it was a pickoff attempt So there is no force out and because of that he is entitled to second base until he moves to third So if you're a defender in this situation the reason it's important that you tag out both runners is because while it is Illegal for both runners to be on the same base at the same time the one who is there illegally Isn't actually out until you tag them. It's not an automatic thing Because of this just play it safe tag them both and let the umpire sort it out You may even get lucky with a couple runners who don't know the rules This may lead them to step off the base at which point you can tag them out because they are off the base on The other hand if you end up in the situation and you're a runner You're kind of out of luck and because again one of you is going to be out But for goodness sakes stay on the base until the umpire calls one of you out and make sure to call time before stepping off So to recap if two runners end up on the same base if the lead runner is forced to the next base Then he is out once he is tagged if on the other hand There is no force out for that lead runner then he is entitled to the base Thus the trailing runner will be the one who is called out