Duplication of files when using Acquia Dev Desktop
C:\Users\Sam\Sites\devdesktop\columbiablooms-dev contains data for your Acquia site (e.g. hooks has scripts that can trigger upon deployment, private contains files that setup as private in Drupal's file system, etc.) 

The C:\Users\Sam\Sites\devdesktop\columbiablooms-dev\docroot dir is the webroot of your site; this is the dir that is the base of your domain that is uploaded to Acquia (e.g. C:\Users\Sam\Sites\devdesktop\columbiablooms-dev\docroot\index.php -> http://www.example.com/index.php). See this post for an explanation of all the subdirectories. 

C:\Users\Sam\Sites\devdesktop\openoutreach-7.x-1.19 is a copy of OpenOutreach 1.19 you downloaded. It contains the OpenOutreach installation profile, its needed modules/themes, and the version of Drupal it's bundled with.