Problem Importing Featured Images

Hello, I have adult tube site and I’m importing posts via CSV importer. I have resolved all problems except one. When I import thumbnails from URL as featured images, all thumbnails are the same. The reason is that in CSV file, all the images has same name, they are just saved in different folders on the host server. I’m trying to solve for 24 hours now how to import these thumbnails. I can get the url of each thumbnail as custom field value, but from there anything I tried did not work. Thanks for help.