Hmm. We'll have to figure out what happened.
Did you take both tests under official testing conditions, including essays and length of breaks? If not, how did you deviate from official conditions for each?
Did you have any timing issues on either test? If you took MGMAT CATs, you can use this article to help you determine whether you had any timing issues:
http://www.manhattangmat.com/blog/index ... ice-tests/What were your quant and verbal subscores? Did both drop on the second test, or was most of the drop due to just one section?
You may also want to read this article for more ideas about what might've gone wrong:
http://www.manhattangmat.com/blog/index ... ent-wrong/Then come back here and tell us what you discovered and we'll help you figure out where to go from there!