diff --git a/machine/corpora/update_usfm_parser_handler.py b/machine/corpora/update_usfm_parser_handler.py
index 71617bc..fafabcc 100644
--- a/machine/corpora/update_usfm_parser_handler.py
+++ b/machine/corpora/update_usfm_parser_handler.py
@@ -104,9 +104,10 @@ def end_usfm(self, state: UsfmParserState) -> None:
         super().end_usfm(state)
 
     def start_book(self, state: UsfmParserState, marker: str, code: str) -> None:
-        self._verse_rows_ref = state.verse_ref.copy()
-        self._update_verse_rows_map()
-        self._update_verse_rows()
+        if self._verse_rows_ref.book_num != state.verse_ref.book_num:
+            self._verse_rows_ref = state.verse_ref.copy()
+            self._update_verse_rows_map()
+            self._update_verse_rows()
 
         self._collect_readonly_tokens(state)
         self._update_block_stack.append(UsfmUpdateBlock())
diff --git a/tests/corpora/test_update_usfm_parser_handler.py b/tests/corpora/test_update_usfm_parser_handler.py
index a81920e..202f522 100644
--- a/tests/corpora/test_update_usfm_parser_handler.py
+++ b/tests/corpora/test_update_usfm_parser_handler.py
@@ -1294,6 +1294,45 @@ def test_duplicate_verses() -> None:
     assert_usfm_equals(target, result)
 
 
+def test_duplicate_id_tags() -> None:
+    rows = [
+        UpdateUsfmRow(scr_ref("MAT 1:0/1:s"), "new section header"),
+        UpdateUsfmRow(scr_ref("MAT 1:1"), "new verse 1"),
+        UpdateUsfmRow(scr_ref("MAT 1:2"), "new verse 2"),
+        UpdateUsfmRow(scr_ref("MAT 1:3"), "new verse 3"),
+        UpdateUsfmRow(scr_ref("MAT 1:4"), "new verse 4"),
+    ]
+    usfm = r"""\id MAT
+\s section header
+\c 1
+\s1 beginning-of-chapter header
+\p
+\v 1 verse 1
+\id
+\v 2 verse 2
+\id MAT
+\v 3 verse 3
+\id MRK
+\v 4 verse 4
+"""
+
+    target = update_usfm(rows, usfm, paragraph_behavior=UpdateUsfmMarkerBehavior.STRIP)
+    result = r"""\id MAT
+\s new section header
+\c 1
+\s1 beginning-of-chapter header
+\p
+\v 1 new verse 1
+\id
+\v 2 new verse 2
+\id MAT
+\v 3 new verse 3
+\id MRK
+\v 4 new verse 4
+"""
+    assert_usfm_equals(target, result)
+
+
 def test_pass_remark():
     rows = [
         UpdateUsfmRow(