diff --git a/NEWS b/NEWS
index 19fd47a3000..3e0eee0d5e5 100644
--- a/NEWS
+++ b/NEWS
@@ -63,6 +63,10 @@ PHP                                                                        NEWS
   . Fix access on NULL pointer in array_merge_recursive(). (ilutov)
   . Fix exception handling in array_multisort(). (ilutov)
 
+- SQLite3:
+  . Fixed bug GH-11451 (Invalid associative array containing duplicate
+    keys). (nielsdos)
+
 08 Jun 2023, PHP 8.2.7
 
 - Core:
diff --git a/ext/sqlite3/sqlite3.c b/ext/sqlite3/sqlite3.c
index d97f8b5fa53..2b9e18d12f1 100644
--- a/ext/sqlite3/sqlite3.c
+++ b/ext/sqlite3/sqlite3.c
@@ -1982,7 +1982,9 @@ PHP_METHOD(SQLite3Result, fetchArray)
 							Z_ADDREF(data);
 						}
 					}
-					zend_symtable_add_new(Z_ARR_P(return_value), result_obj->column_names[i], &data);
+					/* Note: we can't use the "add_new" variant here instead of "update" because
+					 * when the same column name is encountered, the last result should be taken. */
+					zend_symtable_update(Z_ARR_P(return_value), result_obj->column_names[i], &data);
 				}
 			}
 			break;
diff --git a/ext/sqlite3/tests/gh11451.phpt b/ext/sqlite3/tests/gh11451.phpt
new file mode 100644
index 00000000000..e518c39b18b
--- /dev/null
+++ b/ext/sqlite3/tests/gh11451.phpt
@@ -0,0 +1,25 @@
+--TEST--
+GH-11451 (Invalid associative array containing duplicate keys)
+--EXTENSIONS--
+sqlite3
+--FILE--
+<?php
+var_dump((new SQLite3(':memory:'))
+	->query('SELECT 1 AS key, 2 AS key')
+	->fetchArray(SQLITE3_ASSOC));
+
+var_dump((new SQLite3(':memory:'))
+	->query('SELECT 0 AS dummy, 1 AS key, 2 AS key')
+	->fetchArray(SQLITE3_ASSOC));
+?>
+--EXPECT--
+array(1) {
+  ["key"]=>
+  int(2)
+}
+array(2) {
+  ["dummy"]=>
+  int(0)
+  ["key"]=>
+  int(2)
+}