Just like how the skyscraper was lot was vacant at Dorney up until Voodoo was built. Although I am annoyed that a coaster hasn't been gained since 2001 with Talon (since in 2003 Hercules was removed for Hydra and with Voodoo we are losing Laser), Cedar Fair really has added a lot to the park in 15 years
1993 was White Water Landing, 1994 was Thunder Canyon and Road Rally, 1995 and 1996 I am not sure about, 1997 Steel Force, 1998 Hangtime, 1999 Dominator, 2000 Wild Mouse and Camp Snoopy, 2001 Talon, 2002 Meteor, 2003 10 new water slides, 2004 Revolution, 2005 Hydra, 2006 2nd Wave Pool, 2007 Aqua Racer, 2008 Voodoo.
The haven't announced 2009 plans yet.
As for it running 2 trains, I have heard of it happening but in all my visits in 2005, 2006, 2007, 2008 (48) total, I have never seen it run more than 1 train.