You probably had more files selected than you realised when you did the delete. Be very careful with file selection before doing deletes. I always click the files I want again before doing a delete, so that any existing selection based on a View or Smartlist is cleared, and I only delete what I have just manually selected.
Maybe, someone could explain the differences here...
Seriously?
1. The record of the file(s) in the MC Library database is removed from the MC Library database files. The file(s) itself isn't touched.
2. The record of the file(s) in the MC Library database is removed from the MC Library database files and the files on the hard disk are moved to the Recycle Bin.
3. The record of the file(s) in the MC Library database is removed from the MC Library database files and the files on the hard disk are permanently removed from the hard disk, and are not sent to the Recycle Bin. They are unrecoverable, except perhaps via data recovery programs.
Clear now?
GoodSync might be good, however it isn't as good as good Backup Software run in Incremental mode. With good backup software you can recover accidentally deleted files for as long as you have defined you want to keep the backups. You can also pick which version of a file you want to restore, as incremental backups will keep multiple versions.
GoodSync can sort of be used in a safe way as a backup alternative, by setting up a one-way sync and turning off file deletions, as per the GoodSync manual.
https://www.goodsync.com/manual#general_tabPropagate Deletions (checked by default)
If checked, then deletion made by user on one side of the job is propagated to the other side.
If not checked, then deletions are not propagated, only changed files are propagated.
This modifier applies only to 1-way jobs.
That way the destination location you sync to will always have the latest version of the files you want to keep, and also the last version of files you have deleted from the source location.