diff --git a/lib/portage/dbapi/bintree.py b/lib/portage/dbapi/bintree.py
index 180e48c..ab09b42 100644
--- a/lib/portage/dbapi/bintree.py
+++ b/lib/portage/dbapi/bintree.py
@@ -31,6 +31,7 @@
 	ParseError, PortageException
 from portage.localization import _
 from portage.package.ebuild.profile_iuse import iter_iuse_vars
+from portage.util.file_copy import copyfile
 from portage.util.futures import asyncio
 from portage.util.futures.compat_coroutine import coroutine
 from portage.util.futures.executor.fork import ForkExecutor
@@ -483,6 +484,17 @@
 			myoldpkg = catsplit(mycpv)[1]
 			mynewpkg = catsplit(mynewcpv)[1]
 
+			# If this update has already been applied to the same
+			# package build then silently continue.
+			applied = False
+			for maybe_applied in self.dbapi.match('={}'.format(mynewcpv)):
+				if maybe_applied.build_time == mycpv.build_time:
+					applied = True
+					break
+
+			if applied:
+				continue
+
 			if (mynewpkg != myoldpkg) and self.dbapi.cpv_exists(mynewcpv):
 				writemsg(_("!!! Cannot update binary: Destination exists.\n"),
 					noiselevel=-1)
@@ -513,24 +525,34 @@
 					mydata[_unicode_encode(mynewpkg + '.ebuild',
 						encoding=_encodings['repo.content'])] = ebuild_data
 
-			mytbz2.recompose_mem(portage.xpak.xpak_mem(mydata))
-
-			self.dbapi.cpv_remove(mycpv)
-			del self._pkg_paths[self.dbapi._instance_key(mycpv)]
 			metadata = self.dbapi._aux_cache_slot_dict()
 			for k in self.dbapi._aux_cache_keys:
 				v = mydata.get(_unicode_encode(k))
 				if v is not None:
 					v = _unicode_decode(v)
 					metadata[k] = " ".join(v.split())
+
+			# Create a copy of the old version of the package and
+			# apply the update to it. Leave behind the old version,
+			# assuming that it will be deleted by eclean-pkg when its
+			# time comes.
 			mynewcpv = _pkg_str(mynewcpv, metadata=metadata, db=self.dbapi)
-			new_path = self.getname(mynewcpv)
-			self._pkg_paths[
-				self.dbapi._instance_key(mynewcpv)] = new_path[len(self.pkgdir)+1:]
-			if new_path != tbz2path:
-				self._ensure_dir(os.path.dirname(new_path))
-				_movefile(tbz2path, new_path, mysettings=self.settings)
-			self.inject(mynewcpv)
+			update_path = self.getname(mynewcpv, allocate_new=True) + ".partial"
+			self._ensure_dir(os.path.dirname(update_path))
+			update_path_lock = None
+			try:
+				update_path_lock = lockfile(update_path, wantnewlockfile=True)
+				copyfile(tbz2path, update_path)
+				mytbz2 = portage.xpak.tbz2(update_path)
+				mytbz2.recompose_mem(portage.xpak.xpak_mem(mydata))
+				self.inject(mynewcpv, filename=update_path)
+			finally:
+				if update_path_lock is not None:
+					try:
+						os.unlink(update_path)
+					except OSError:
+						pass
+					unlockfile(update_path_lock)
 
 		return moves
 
diff --git a/lib/portage/emaint/modules/move/move.py b/lib/portage/emaint/modules/move/move.py
index 8fc3269..2a95e99 100644
--- a/lib/portage/emaint/modules/move/move.py
+++ b/lib/portage/emaint/modules/move/move.py
@@ -1,4 +1,4 @@
-# Copyright 2005-2020 Gentoo Authors
+# Copyright 2005-2021 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 from _emerge.Package import Package
@@ -76,7 +76,16 @@
 						except (KeyError, InvalidData):
 							continue
 						if repo_match(cpv.repo):
-							errors.append("'%s' moved to '%s'" % (cpv, newcp))
+							build_time = getattr(cpv, 'build_time', None)
+							if build_time is not None:
+								# If this update has already been applied to the same
+								# package build then silently continue.
+								for maybe_applied in match('={}'.format(
+									cpv.replace(cpv.cp, str(newcp), 1))):
+									if maybe_applied.build_time == build_time:
+										break
+								else:
+									errors.append("'%s' moved to '%s'" % (cpv, newcp))
 				elif update_cmd[0] == "slotmove":
 					pkg, origslot, newslot = update_cmd[1:]
 					atom = pkg.with_slot(origslot)
diff --git a/lib/portage/tests/update/test_move_ent.py b/lib/portage/tests/update/test_move_ent.py
index d9647a9..d9036db 100644
--- a/lib/portage/tests/update/test_move_ent.py
+++ b/lib/portage/tests/update/test_move_ent.py
@@ -1,4 +1,4 @@
-# Copyright 2012-2013 Gentoo Foundation
+# Copyright 2012-2021 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 import textwrap
@@ -93,8 +93,9 @@
 			self.assertRaises(KeyError,
 				vardb.aux_get, "dev-libs/A-1", ["EAPI"])
 			vardb.aux_get("dev-libs/A-moved-1", ["EAPI"])
-			self.assertRaises(KeyError,
-				bindb.aux_get, "dev-libs/A-1", ["EAPI"])
+			# The original package should still exist because a binary
+			# package move is a copy on write operation.
+			bindb.aux_get("dev-libs/A-1", ["EAPI"])
 			bindb.aux_get("dev-libs/A-moved-1", ["EAPI"])
 
 			# dont_apply_updates