Display two Views blocks with equal height
Try using the equal heights module 


  This module implements a jQuery Equal Heights plugin that can equalize
  the height of the elements of the specified class.
  
  To use it, give the elements the same class, then go to the
  administration interface and add this class (separate multiple classes
  by a space). By default, it sets the height to the height of the
  tallest element but you can also specify minimum and maximum height.


To use the just give both the blocks the same class and add the admin name in the admin interface of the module and then js will do the rest.