diff --git a/src/calibre/devices/kindle/driver.py b/src/calibre/devices/kindle/driver.py
index a84e160c67..a2b9bd5511 100644
--- a/src/calibre/devices/kindle/driver.py
+++ b/src/calibre/devices/kindle/driver.py
@@ -8,7 +8,7 @@ __docformat__ = 'restructuredtext en'
 Device driver for Amazon's Kindle
 '''
 
-import datetime, os, re, sys, json, hashlib, shutil
+import datetime, os, re, sys, json, hashlib
 
 from calibre.constants import DEBUG
 from calibre.devices.kindle.bookmark import Bookmark
@@ -38,10 +38,6 @@ file metadata.
 '''
 
 
-def get_kfx_path(path):
-    return os.path.dirname(os.path.dirname(path)).rpartition('.')[0] + '.kfx'
-
-
 class KINDLE(USBMS):
 
     name           = 'Kindle Device Interface'
@@ -86,40 +82,30 @@ class KINDLE(USBMS):
         ' Click "Show details" to see the list of books.'
     )
 
-    def is_a_book_file(self, filename, path, prefix):
+    def is_allowed_book_file(self, filename, path, prefix):
         lpath = os.path.join(path, filename).partition(self.normalize_path(prefix))[2].replace('\\', '/')
-        return lpath.endswith('.sdr/assets/metadata.kfx')
-
-    def delete_single_book(self, path):
-        if path.replace('\\', '/').endswith('.sdr/assets/metadata.kfx'):
-            kfx_path = get_kfx_path(path)
-            if DEBUG:
-                prints('Kindle driver: Attempting to delete kfx: %r -> %r' % (path, kfx_path))
-            if os.path.exists(kfx_path):
-                os.unlink(kfx_path)
-            sdr_path = kfx_path.rpartition('.')[0] + '.sdr'
-            if os.path.exists(sdr_path):
-                shutil.rmtree(sdr_path)
-            try:
-                os.removedirs(os.path.dirname(kfx_path))
-            except Exception:
-                pass
-
-        else:
-            return USBMS.delete_single_book(self, path)
+        return '.sdr/' not in lpath
 
     @classmethod
     def metadata_from_path(cls, path):
-        if path.replace('\\', '/').endswith('.sdr/assets/metadata.kfx'):
+        if path.endswith('.kfx'):
             from calibre.ebooks.metadata.kfx import read_metadata_kfx
             try:
-                with lopen(path, 'rb') as f:
-                    mi = read_metadata_kfx(f)
+                kfx_path = path
+                with lopen(kfx_path, 'rb') as f:
+                    if f.read(8) != b'\xeaDRMION\xee':
+                        f.seek(0)
+                        mi = read_metadata_kfx(f)
+                    else:
+                        kfx_path = os.path.join(path.rpartition('.')[0] + '.sdr', 'assets', 'metadata.kfx')
+                        with lopen(kfx_path, 'rb') as mf:
+                            mi = read_metadata_kfx(mf)
             except Exception:
                 import traceback
                 traceback.print_exc()
-                path = get_kfx_path(path)
-                mi = cls.metadata_from_formats([get_kfx_path(path)])
+                if DEBUG:
+                    prints('failed kfx path:', kfx_path)
+                mi = cls.metadata_from_formats([path])
         else:
             mi = cls.metadata_from_formats([path])
         if mi.title == _('Unknown') or ('-asin' in mi.title and '-type' in mi.title):
diff --git a/src/calibre/devices/usbms/driver.py b/src/calibre/devices/usbms/driver.py
index bb23608e1a..c3c57c9e21 100644
--- a/src/calibre/devices/usbms/driver.py
+++ b/src/calibre/devices/usbms/driver.py
@@ -177,8 +177,8 @@ class USBMS(CLI, Device):
     def formats_to_scan_for(self):
         return set(self.settings().format_map) | set(self.FORMATS)
 
-    def is_a_book_file(self, filename, path, prefix):
-        return False
+    def is_allowed_book_file(self, filename, path, prefix):
+        return True
 
     def books(self, oncard=None, end_session=True):
         from calibre.ebooks.metadata.meta import path_to_ext
@@ -222,7 +222,7 @@ class USBMS(CLI, Device):
 
         def update_booklist(filename, path, prefix):
             changed = False
-            if path_to_ext(filename) in all_formats or self.is_a_book_file(filename, path, prefix):
+            if path_to_ext(filename) in all_formats and self.is_allowed_book_file(filename, path, prefix):
                 try:
                     lpath = os.path.join(path, filename).partition(self.normalize_path(prefix))[2]
                     if lpath.startswith(os.sep):
diff --git a/src/calibre/ebooks/metadata/kfx.py b/src/calibre/ebooks/metadata/kfx.py
index f6bb24557b..66eeadec71 100644
--- a/src/calibre/ebooks/metadata/kfx.py
+++ b/src/calibre/ebooks/metadata/kfx.py
@@ -38,6 +38,7 @@ DT_STRING = 8           # unicode
 DT_STRUCT = 11          # tuple
 DT_LIST = 12            # list
 DT_OBJECT = 13          # dict of property/value pairs
+DT_TYPED_DATA = 14      # type, name, value
 
 # property names (non-unicode strings to distinguish them from ION strings in this program)
 # These are place holders. The correct property names are unknown.
@@ -52,7 +53,7 @@ METADATA_PROPERTIES = {
     b'P10' : "languages",
     b'P153': "title",
     b'P154': "description",
-    b'P222': "authors",
+    b'P222': "author",
     b'P232': "publisher",
 }
 
@@ -217,6 +218,12 @@ class PackedIon(PackedData):
 
             return result
 
+        if data_type == DT_TYPED_DATA:
+            ion = PackedIon(self.extract(data_len))
+            ion.unpack_number()
+            ion.unpack_number()
+            return ion.unpack_typed_value()
+
         # ignore unknown types
         self.advance(data_len)
         return None
@@ -289,7 +296,7 @@ def read_metadata_kfx(stream, read_cover=True):
         return ans
 
     title = get('title') or _('Unknown')
-    authors = get('authors', False) or [_('Unknown')]
+    authors = get('author', False) or [_('Unknown')]
     auth_pat = re.compile(r'([^,]+?)\s*,\s+([^,]+)$')
 
     def fix_author(x):
@@ -299,7 +306,12 @@ def read_metadata_kfx(stream, read_cover=True):
                 return m.group(2) + ' ' + m.group(1)
         return x
 
-    mi = Metadata(title, [fix_author(x) for x in authors])
+    unique_authors = []     # remove duplicates while retaining order
+    for f in [fix_author(x) for x in authors]:
+        if f not in unique_authors:
+            unique_authors.append(f)
+
+    mi = Metadata(title, unique_authors)
     if has('author'):
         mi.author_sort = get('author')
     if has('ASIN'):