Can you link up twice in one turn in Age of Steam?
I have the game, and dug out the rules to clarify.

Under section 5, Move Goods, it states the following:


  In ONE of the two opportunities to Move Goods, the player may instead
  opt to move their disk on the Engine Track up one link. The maximum
  number of links is still 6 links.


Therefore, you may not use the Increase Engine Link option twice, and move no goods.