v7.3: repeated mirror job deleted all files at destination

[tubemirror]

Hi,
1st of all many thanks for this great software, I am using it since many years successfully and never had an issue.
Maybe you can help me with this topic, many thanks upfront.
I am using v7.3 on Windows 7 Sp1.
Yesterday I had 1st time issues with a mirror job.

I mirrored files from one 2TB disk to another 2TB - (vol K: and S: to one NTFS filesystem on L:).
Mirror options simply by timestamp of the files, not per content, as this never was required.
This took about 2,5 hours.
During the mirror I continued to work on computer, got i.e. new mails in.
So I decided to repeat this mirror job, to be sure, that the latest changes are mirrored.

When repeating this mirror it looked already a little strange in regards to the amount of changes, but I didnt care about, because FreeFile Sync is very reliable, I didnt change any settings and simply repeated the synchronization directly after the 1st job just had terminated. The FreeFileSync Windows was still opened. So with exactly the same settings I repeated the mirror,
RESULT & Problem: This 2nd mirror job deleted all files at the destination which is weired.
Luckily no change or loss on the 2 source volumes.

Do you have any clue what might have happened ?

I get a warning when starting the mirror (translated from german): several folder pairs write into the same subfolder, please check your configuration. In regards to my "visible" user data folder I see no issues by this.
Is perhaps some hidden folder information being copied, so that I overwrite hidden data of the 2 source volumes which lead to strange / inconsistant results in the destination ?

I bought a new 2 TB Disk to be able to consolidate data from old 2TB disk with 2 different filesystems
to another 2TB disk, where I have only 1 NTFS, one of the filesystems became too small ...

[Zenju]

several folder pairs write into the same subfolder

This warning is generally an indication for a configuration error that is causing the unexpected delete. E.g. if you have a setup with two folder pairs like:
A -> C
B -> C
Then the second sync will delete all files in C that exist in A but not in B and also delete files that exist in B and not in A, similarly to what you described. The solution is to use the appropriate file inclusion/exclusion filters for each folder pair.