Overwrote... but why?

Lots of problems with this.
I'm running mirror(update) preview (equalise does the same as output 2). When I do source A dest B, I get the first output. Source B dest A gets the second output. File drums.gif (oops not shown) is overwritten even though it has the same MD5, and the timestamp is only one second off.

Is this a bug? Can I prevent it by checking 'retain attributes'?

output #1
------------
Starting...

Copied \search.htm

Removed D:\Documents\desktop.ini
Preview Finished...
Finished...

output #2
----------
Starting...

Overwrote \hobo_signs.pdf
[bunch of similar 'overwrote' lines - 15 or so]
Copied \desktop.ini
[bunch of similar 'overwrote' lines - 200 or so]
Overwrote \fingerabdruck_kopieren.xml.htm

Removed and Settings\Administrator\My Documents\search.htm
Preview Finished...
Finished...

----------