diff --git a/src/calibre/gui2/actions/add.py b/src/calibre/gui2/actions/add.py
index 4c639ec0bd..cfe65c8c2a 100644
--- a/src/calibre/gui2/actions/add.py
+++ b/src/calibre/gui2/actions/add.py
@@ -11,7 +11,7 @@ from collections import defaultdict
 from functools import partial
 from qt.core import QApplication, QDialog, QPixmap, QTimer
 
-from calibre import as_unicode, guess_type
+from calibre import as_unicode, guess_type, prepare_string_for_xml
 from calibre.constants import iswindows
 from calibre.ebooks import BOOK_EXTENSIONS
 from calibre.ebooks.metadata import MetaInformation, normalize_isbn
@@ -574,10 +574,10 @@ class AddAction(InterfaceAction):
                 merged[author].append(title)
             lines = []
             for author in sorted(merged, key=sort_key):
-                lines.append(author)
-                for title in sorted(merged[author], key=sort_key):
-                    lines.append('  ' + title)
-                lines.append('')
+                lines.append(f'<b><i>{prepare_string_for_xml(author)}</i></b><ol style="margin-top: 0">')
+                for title in sorted(merged[author]):
+                    lines.append(f'<li>{prepare_string_for_xml(title)}</li>')
+                lines.append('</ol>')
             pm = ngettext('The following duplicate book was found.',
                           'The following {} duplicate books were found.',
                           len(adder.merged_books)).format(len(adder.merged_books))
diff --git a/src/calibre/gui2/dialogs/message_box.py b/src/calibre/gui2/dialogs/message_box.py
index 1b6f4dc11a..64a6e164c2 100644
--- a/src/calibre/gui2/dialogs/message_box.py
+++ b/src/calibre/gui2/dialogs/message_box.py
@@ -494,7 +494,16 @@ class JobError(QDialog):  # {{{
 
 if __name__ == '__main__':
     from calibre.gui2 import Application, question_dialog
+    from calibre import prepare_string_for_xml
     app = Application([])
+    merged = {'Kovid Goyal': ['Waterloo', 'Doomed'], 'Someone Else': ['Some other book ' * 1000]}
+    lines = []
+    for author in sorted(merged):
+        lines.append(f'<b><i>{prepare_string_for_xml(author)}</i></b><ol style="margin-top: 0">')
+        for title in sorted(merged[author]):
+            lines.append(f'<li>{prepare_string_for_xml(title)}</li>')
+        lines.append('</ol>')
+
     print(question_dialog(None, 'title', 'msg <a href="http://google.com">goog</a> ',
-            det_msg='<p>hi there <b>guy</b> '*1000,
+            det_msg='\n'.join(lines),
             show_copy_button=True))