As per some comments and reports:
If you change a file in an already uploaded asset (for example clothes), you risk getting the new file renamed "..._0". This is a drupal quirk. (if you're interested, see discussion at https://www.drupal.org/node/1924686). The problem is that if you "remove" a file, it isn't actually removed until you save the node. Which means that the new upload is considered a copy or separate entity.
To avoid this, you need to:
1. Edit the particular node (for example clothes)
2. Click "remove" on the file you want to change
3. Click save on the node
4. Edit the node again
5. Upload the new version of the file.
6. Click save
I haven't found a way to avoid this so far (it's annoyingly cumbersome to have to edit the post twice just to change files). But investigations are ongoing.