When exporting resources file that contains definitions of strings with attribute translatable=false they make it into the .po file.
This seems like an undesirable behavior as the attribute clearly states that given string should not be translated thus it should not be written to the *.po file.
It would be really nice to see this added.
And in the meantime there is a simple workaround, it is enough to place your non-translatable strings in the donottranslate.xml file(see http://tools.android.com/recent/non-translatablestrings).