Moving / Migrating image files from another site into an existing Drupal 7 site
Why not use Feed Import  I am using it to import content from Joomla and WP sites into new Drupal sites with Drupal to Drupal export import should be a lot easy.
My process is as follows:


Create desired content types with all matching fields on the new
site.
Create Import profile for this content type go to mystie/import to
download csv template
Export content from the old site with path to images so to have
matching content with image
Upload images to new web site and change paths in csv file
Import and create or update content.