Add test case for OR filter duplicate results issue

Co-authored-by: anidotnet <696662+anidotnet@users.noreply.github.com>

Author: Copilot

nitrite/src/test/java/org/dizitart/no2/integration/collection/IssueTest.java

@@ -2,14 +2,20 @@
 
 import org.dizitart.no2.Nitrite;
 import org.dizitart.no2.collection.Document;
+import org.dizitart.no2.collection.DocumentCursor;
 import org.dizitart.no2.collection.NitriteCollection;
+import org.dizitart.no2.filters.Filter;
 import org.dizitart.no2.filters.FluentFilter;
 import org.dizitart.no2.index.IndexOptions;
 import org.dizitart.no2.index.IndexType;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
 import static org.junit.Assert.assertEquals;
 
 public class IssueTest {
@@ -47,4 +53,32 @@ public void testOriginalIssue() {
         assertEquals(1, collection.find(FluentFilter.where("value").lte(42L)).size());
         assertEquals(1, collection.find(FluentFilter.where("value").gte(42L)).size());
     }
+
+    @Test
+    public void testMultipleIndexesOrFilterDuplicates() {
+        NitriteCollection items = db.getCollection("items");
+        items.createIndex(IndexOptions.indexOptions(IndexType.NON_UNIQUE), "field_a");
+        items.createIndex(IndexOptions.indexOptions(IndexType.NON_UNIQUE), "field_b");
+
+        Document doc = Document.createDocument();
+        doc.put("field_a", "A");
+        doc.put("field_b", "B");
+        items.insert(doc);
+
+        Filter aFilter = FluentFilter.where("field_a").eq("A");
+        Filter bFilter = FluentFilter.where("field_b").eq("B");
+
+        Filter orFilter = Filter.or(aFilter, bFilter);
+
+        DocumentCursor cursor = items.find(orFilter);
+        Iterator<Document> docIter = cursor.iterator();
+
+        List<Long> matches = new ArrayList<>();
+        while (docIter.hasNext()) {
+            Document match = docIter.next();
+            long id = match.getId().getIdValue();
+            matches.add(id);
+        }
+        assertEquals("Single document must yield single match", 1, matches.size());
+    }
 }