diff --git a/xCAT-server/lib/perl/xCAT/Postage.pm b/xCAT-server/lib/perl/xCAT/Postage.pm
index 5fda1acfd..6da8b3277 100644
--- a/xCAT-server/lib/perl/xCAT/Postage.pm
+++ b/xCAT-server/lib/perl/xCAT/Postage.pm
@@ -214,6 +214,11 @@ sub defer_syncfiles_to_postboot {
       unless defined($postscripts) && $postscripts =~ s/^[ \t]*syncfiles[ \t]*\n//m;
 
     $postbootscripts = "" unless defined $postbootscripts;
+
+    # A node may already list syncfiles as a postbootscript of its own; do not add a second copy.
+    return ($postscripts, $postbootscripts)
+      if $postbootscripts =~ /^[ \t]*syncfiles[ \t]*$/m;
+
     $postbootscripts =
         "# ubuntu-deferred-postbootscripts-start-here\nsyncfiles\n# ubuntu-deferred-postbootscripts-end-here\n"
       . $postbootscripts;
diff --git a/xCAT-test/unit/postage_ubuntu_syncfiles_postboot.t b/xCAT-test/unit/postage_ubuntu_syncfiles_postboot.t
index e0e935ffb..9962ea20c 100644
--- a/xCAT-test/unit/postage_ubuntu_syncfiles_postboot.t
+++ b/xCAT-test/unit/postage_ubuntu_syncfiles_postboot.t
@@ -83,6 +83,16 @@ foreach my $case (@untouched) {
     is($postboot, $DEFERRED, 'an undefined postbootscripts list becomes the deferral block');
 }
 
+# A node that already lists syncfiles as its own postbootscript keeps that entry, and does not
+# gain a second one -- the install-time copy is still removed, since that is the one that cannot work.
+{
+    my ($post, $postboot) =
+      defer('ubuntu24.04', 'install', 'install', "syncfiles\nfoo\n", "syncfiles\nsetupntp\n");
+    is($post, "foo\n", 'the postscripts entry is still removed');
+    is($postboot, "syncfiles\nsetupntp\n",
+        "an admin's own syncfiles postbootscript is left as it was, not duplicated");
+}
+
 # Rendering the same node twice must not stack a second copy.
 {
     my ($post, $postboot) =