What are the rules for mexican train dominoes?

Mexican Train Dominoes Rules Help?

• Someone could not play on there own train in the game and put there penny up. So the next person plays a double on the 1st persons train but does not clear it( this version you can not play a double on one train and the match to another) does the person that did not clear the double have to put a penny up as well? Please don't answer unless you know how to play the game and know the rules of the game.

• Answer:

  the 2nd person would have to put their penny up and because it was a double, play would not have been able to continue until someone completed the double.