diff --git a/collect_app/src/main/java/org/odk/collect/android/database/entities/DatabaseEntitiesRepository.kt b/collect_app/src/main/java/org/odk/collect/android/database/entities/DatabaseEntitiesRepository.kt
index 57dc54a8de3..b3e127ca42c 100644
--- a/collect_app/src/main/java/org/odk/collect/android/database/entities/DatabaseEntitiesRepository.kt
+++ b/collect_app/src/main/java/org/odk/collect/android/database/entities/DatabaseEntitiesRepository.kt
@@ -383,6 +383,7 @@ class DatabaseEntitiesRepository(context: Context, dbPath: String) : EntitiesRep
         val missingColumns = entity.properties
             .map { EntitiesTable.getPropertyColumn(it.first) }
             .filterNot { columnNames.contains(it) }
+            .distinctBy { it.lowercase() }
 
         if (missingColumns.isNotEmpty()) {
             databaseConnection.resetTransaction {
diff --git a/collect_app/src/test/java/org/odk/collect/android/entities/EntitiesRepositoryTest.kt b/collect_app/src/test/java/org/odk/collect/android/entities/EntitiesRepositoryTest.kt
index 6b9d3d27c72..018721f55e3 100644
--- a/collect_app/src/test/java/org/odk/collect/android/entities/EntitiesRepositoryTest.kt
+++ b/collect_app/src/test/java/org/odk/collect/android/entities/EntitiesRepositoryTest.kt
@@ -644,4 +644,19 @@ abstract class EntitiesRepositoryTest {
         repository.updateListHash("wine", "2024")
         assertThat(repository.getListHash("wine"), equalTo("2024"))
     }
+
+    @Test
+    fun `#save ignores case-insensitive duplicate properties`() {
+        val repository = buildSubject()
+        val entity = Entity.New(
+            "1",
+            "One",
+            properties = listOf(Pair("prop", "value"), Pair("Prop", "value"))
+        )
+
+        repository.save("things", entity)
+        val savedEntities = repository.getEntities("things")
+        assertThat(savedEntities[0].properties.size, equalTo(1))
+        assertThat(savedEntities[0].properties[0].first, equalTo("prop"))
+    }
 }
diff --git a/entities/src/main/java/org/odk/collect/entities/storage/InMemEntitiesRepository.kt b/entities/src/main/java/org/odk/collect/entities/storage/InMemEntitiesRepository.kt
index 4ea4afd4f29..e467df1a104 100644
--- a/entities/src/main/java/org/odk/collect/entities/storage/InMemEntitiesRepository.kt
+++ b/entities/src/main/java/org/odk/collect/entities/storage/InMemEntitiesRepository.kt
@@ -123,7 +123,12 @@ class InMemEntitiesRepository : EntitiesRepository {
         lists.add(list)
         listProperties.getOrPut(list) {
             mutableSetOf()
-        }.addAll(entity.properties.map { it.first })
+        }.addAll(
+            entity
+                .properties
+                .distinctBy { it.first.lowercase() }
+                .map { it.first }
+        )
     }
 
     private fun mergeProperties(