I used the following script to backup/restore site collections
Backup-SPSite -Identity "http://domain" -Path "C:\backup\domain.bak" -Force -NoSiteLock
then I run this command to restore to another domain
Restore-SPSite http://anotherdomain -Path C:\backup\domain.bak -DatabaseName "domain_db " -HostHeaderWebApplication http://appurl -Force -DatabaseServer db_server_domain
Site that I backed up was around 700MB. It had some hundreds of photos. I restored the backup file to another domain and deleted all those folders under Photo Galleries
(and also emptied all recycle bins). But when I create a backup file for second domain (which should not contain deleted photos) it's 700MB again. I check the folders using Design Manager and I don't see files there. Folders are empty.
Content database is also 900MB (database has only one site collection)
Why I get 700MB backup file for a site that is completely empty?