Both the Windows and the OS X versions need a copy of tessdata — it's required for OCR — so you can't remove it from uploader\src\main\resources\tessdata because that will break the Windows build (you can test this by viewing the Play screen in Ranked mode, which triggers OCR on the rank... if tessdata is missing then the uploader will crash). 

If you're keen to keep only one copy, then it might be possible to put it into the uploader jar, then have the Ant script in uploader-osx extract the files from the jar and put them into the OS X app bundle... but it's not a high priority for me.