How to fix 'Cannot redeclare ctools_content_process' problem after sql-sync?
In Drupal 7; this could be caused by corruption in the code registry. The code registry


  is an inventory of all classes and interfaces for all enabled modules
  and Drupal's core files. The registry stores the path to the file a
  given class or interface is defined in, and loads the file when
  necessary.


ref: Drupal Code Registry

The solution to this particular problem would be to force a rebuild of the registry; which you can do as per this post; Code Registry Rebuild.