Hi Hossein,
2011.03.01 19:08, Hossein Noorikhah rašė:
While translating LibO, I encountered many duplicate strings. Now that I'm
translating "Extensions for LibO 3.3", there are a lot of empty strings. I
think both -empty and duplicate strings- are problems.
Please see the attached screenshot.
Yes, there are a few empty strings. You can figure out their meaning
from the comment/identifier – they are tooltips for certain UI elements.
If you want those elements to have tooltips, you can "translate" the
strings. If not, just leave them empty.
Similarly, duplicate strings may be duplicates, but they likely appear
in different contexts, so it's probably good that they are separate.
Hope this helps. However, if you think some of those duplicates are
indeed bugs, feel free to disagree with me. 
Rimas