-test_begin_subtest 'Duplicated message is tagged according to the duplicate'
-cp "$MAIL_DIR/cur/msg-003" "$MAIL_DIR/cur/msg-003-dup:2,RS"
-increment_mtime $MAIL_DIR/cur
+test_begin_subtest 'Adding flags to duplicate message tags the mail'
+add_message [subject]='"Duplicated message"' [dir]=cur [filename]='duplicated-message:2,'
+cp "$MAIL_DIR/cur/duplicated-message:2," "$MAIL_DIR/cur/duplicated-message-copy:2,RS"
+increment_mtime $MAIL_DIR/cur
+NOTMUCH_NEW > output
+notmuch search subject:"Duplicated message" | notmuch_search_sanitize >> output
+test_expect_equal "$(< output)" "No new mail.
+thread:XXX 2001-01-05 [1/1] Notmuch Test Suite; Duplicated message (inbox replied)"
+
+test_begin_subtest "Duplicate mail with new flags propagates flag to original file"
+(cd $MAIL_DIR/cur/; ls duplicated*) > actual
+test_expect_equal "$(< actual)" "duplicated-message:2,RS
+duplicated-message-copy:2,RS"
+
+test_begin_subtest "Adding duplicate message without flags does not remove tags"
+cp "$MAIL_DIR/cur/duplicated-message-copy:2,RS" "$MAIL_DIR/cur/duplicated-message-another-copy:2,"
+increment_mtime $MAIL_DIR/cur