These have been added by 36d7b40c, before we had always UNIX only. poedit can read the mixed files just fine, but python polib (which is used in po/lyx_pot.py) refuses to load files with mixed endings.
36d7b40c
- to start the translation work - sk and it are already work in progress
to dinstinguish the 2 different pt variants. We do already the same for Chinese (zh). No further change should be necessary.