diff --git a/telethon/sessions/abstract.py b/telethon/sessions/abstract.py
index ec4f649f..89f80b7a 100644
--- a/telethon/sessions/abstract.py
+++ b/telethon/sessions/abstract.py
@@ -18,8 +18,8 @@ class Session(ABC):
         self._report_errors = True
         self._flood_sleep_threshold = 60
 
-    def clone(self):
-        cloned = self.__class__()
+    def clone(self, to_instance=None):
+        cloned = to_instance or self.__class__()
         cloned._device_model = self.device_model
         cloned._system_version = self.system_version
         cloned._app_version = self.app_version
@@ -27,6 +27,7 @@ class Session(ABC):
         cloned._system_lang_code = self.system_lang_code
         cloned._report_errors = self.report_errors
         cloned._flood_sleep_threshold = self.flood_sleep_threshold
+        return cloned
 
     @abstractmethod
     def set_dc(self, dc_id, server_address, port):
diff --git a/telethon/sessions/memory.py b/telethon/sessions/memory.py
index 09aa1fa0..92674fa6 100644
--- a/telethon/sessions/memory.py
+++ b/telethon/sessions/memory.py
@@ -111,8 +111,41 @@ class MemorySession(Session):
     def list_sessions(cls):
         raise NotImplementedError
 
-    @staticmethod
-    def _entities_to_rows(tlo):
+    def _entity_values_to_row(self, id, hash, username, phone, name):
+        return id, hash, username, phone, name
+
+    def _entity_to_row(self, e):
+        if not isinstance(e, TLObject):
+            return
+        try:
+            p = utils.get_input_peer(e, allow_self=False)
+            marked_id = utils.get_peer_id(p)
+        except ValueError:
+            return
+
+        if isinstance(p, (InputPeerUser, InputPeerChannel)):
+            if not p.access_hash:
+                # Some users and channels seem to be returned without
+                # an 'access_hash', meaning Telegram doesn't want you
+                # to access them. This is the reason behind ensuring
+                # that the 'access_hash' is non-zero. See issue #354.
+                # Note that this checks for zero or None, see #392.
+                return
+            else:
+                p_hash = p.access_hash
+        elif isinstance(p, InputPeerChat):
+            p_hash = 0
+        else:
+            return
+
+        username = getattr(e, 'username', None) or None
+        if username is not None:
+            username = username.lower()
+        phone = getattr(e, 'phone', None)
+        name = utils.get_display_name(e) or None
+        return self._entity_values_to_row(marked_id, p_hash, username, phone, name)
+
+    def _entities_to_rows(self, tlo):
         if not isinstance(tlo, TLObject) and utils.is_list_like(tlo):
             # This may be a list of users already for instance
             entities = tlo
@@ -127,35 +160,9 @@ class MemorySession(Session):
 
         rows = []  # Rows to add (id, hash, username, phone, name)
         for e in entities:
-            if not isinstance(e, TLObject):
-                continue
-            try:
-                p = utils.get_input_peer(e, allow_self=False)
-                marked_id = utils.get_peer_id(p)
-            except ValueError:
-                continue
-
-            if isinstance(p, (InputPeerUser, InputPeerChannel)):
-                if not p.access_hash:
-                    # Some users and channels seem to be returned without
-                    # an 'access_hash', meaning Telegram doesn't want you
-                    # to access them. This is the reason behind ensuring
-                    # that the 'access_hash' is non-zero. See issue #354.
-                    # Note that this checks for zero or None, see #392.
-                    continue
-                else:
-                    p_hash = p.access_hash
-            elif isinstance(p, InputPeerChat):
-                p_hash = 0
-            else:
-                continue
-
-            username = getattr(e, 'username', None) or None
-            if username is not None:
-                username = username.lower()
-            phone = getattr(e, 'phone', None)
-            name = utils.get_display_name(e) or None
-            rows.append((marked_id, p_hash, username, phone, name))
+            row = self._entity_to_row(e)
+            if row:
+                rows.append(row)
         return rows
 
     def process_entities(self, tlo):
diff --git a/telethon/sessions/sqlite.py b/telethon/sessions/sqlite.py
index 64f3cbf6..0ea26ae5 100644
--- a/telethon/sessions/sqlite.py
+++ b/telethon/sessions/sqlite.py
@@ -120,8 +120,8 @@ class SQLiteSession(MemorySession):
             c.close()
             self.save()
 
-    def clone(self):
-        cloned = super().clone()
+    def clone(self, to_instance=None):
+        cloned = super().clone(to_instance)
         cloned.save_entities = self.save_entities
         return cloned
 
@@ -180,9 +180,7 @@ class SQLiteSession(MemorySession):
     # Data from sessions should be kept as properties
     # not to fetch the database every time we need it
     def set_dc(self, dc_id, server_address, port):
-        self._dc_id = dc_id
-        self._server_address = server_address
-        self._port = port
+        super().set_dc(dc_id, server_address, port)
         self._update_session_table()
 
         # Fetch the auth_key corresponding to this data center
@@ -287,16 +285,19 @@ class SQLiteSession(MemorySession):
             'select id, hash from entities where phone=?', (phone,))
 
     def get_entity_rows_by_username(self, username):
-        self._fetchone_entity('select id, hash from entities where username=?',
-                              (username,))
+        return self._fetchone_entity(
+            'select id, hash from entities where username=?',
+            (username,))
 
     def get_entity_rows_by_name(self, name):
-        self._fetchone_entity('select id, hash from entities where name=?',
-                              (name,))
+        return self._fetchone_entity(
+            'select id, hash from entities where name=?',
+            (name,))
 
     def get_entity_rows_by_id(self, id):
-        self._fetchone_entity('select id, hash from entities where id=?',
-                              (id,))
+        return self._fetchone_entity(
+            'select id, hash from entities where id=?',
+            (id,))
 
     # File processing