I have 3 HDDs. One is the main system drive and the other two (same model number and capacity) are meant for backups. I synchronize the two using Microsoft's Synctoy. However, even when I use the echo option in Synctoy one HDD appears to use more space than the other. One reason may be because I did some backups on it (and these backups refused to be synced to the other HDD). However, even though I deleted the backups the HDD still shows as having less space than the one it syncs with. I've already gone into the folder options to show hidden files and folders but I still cannot see these (supposed) backup folders. Any other way?