diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8fc524f6b..0773e3a08 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -54,6 +54,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Sort paginated query field rows by document view id [#354](https://github.com/p2panda/aquadoggo/pull/354)
 - Fix missing field when filtering owner [#359](https://github.com/p2panda/aquadoggo/pull/359)
 - Bind untrusted user filter arguments in SQL query [#358](https://github.com/p2panda/aquadoggo/pull/358)
+- Handle duplicate document view insertions in reduce task [#410](https://github.com/p2panda/aquadoggo/pull/410)
 
 ## [0.4.0]
 
diff --git a/aquadoggo/src/db/stores/document.rs b/aquadoggo/src/db/stores/document.rs
index 39dc6efd5..afce47dc1 100644
--- a/aquadoggo/src/db/stores/document.rs
+++ b/aquadoggo/src/db/stores/document.rs
@@ -459,7 +459,6 @@ async fn insert_document_view(
             )
         VALUES
             ($1, $2, $3)
-        ON CONFLICT(document_view_id) DO NOTHING -- @TODO: temp fix for double document view insertions: https://github.com/p2panda/aquadoggo/issues/398
         ",
     )
     .bind(document_view.id().to_string())
diff --git a/aquadoggo/src/materializer/tasks/reduce.rs b/aquadoggo/src/materializer/tasks/reduce.rs
index db3ff12e1..1f750a686 100644
--- a/aquadoggo/src/materializer/tasks/reduce.rs
+++ b/aquadoggo/src/materializer/tasks/reduce.rs
@@ -36,6 +36,21 @@ use crate::materializer::TaskInput;
 pub async fn reduce_task(context: Context, input: TaskInput) -> TaskResult<TaskInput> {
     debug!("Working on {}", input);
 
+    // If this task is concerned with a document view then we can first check if it has actually
+    // already been materialized. If so, we exit this task immediately and return no new tasks.
+    if let Some(document_view_id) = &input.document_view_id {
+        let document_view_exists = context
+            .store
+            .get_document_by_view_id(document_view_id)
+            .await
+            .map_err(|err| TaskError::Critical(err.to_string()))?
+            .is_some();
+
+        if document_view_exists {
+            return Ok(None);
+        }
+    }
+
     // Find out which document we are handling
     let document_id = match resolve_document_id(&context, &input).await? {
         Some(document_id) => Ok(document_id),
@@ -513,4 +528,38 @@ mod tests {
             assert!(reduce_task(node.context.clone(), input).await.is_ok());
         });
     }
+
+    #[rstest]
+    fn duplicate_document_view_insertions(
+        #[from(populate_store_config)]
+        #[with(2, 1, 1)]
+        config: PopulateStoreConfig,
+    ) {
+        test_runner(|node: TestNode| async move {
+            // Populate the store with some entries and operations but DON'T materialise any resulting documents.
+            let (_, document_ids) = populate_store(&node.context.store, &config).await;
+            let document_id = document_ids.get(0).expect("At least one document id");
+
+            // Get the operations and build the document.
+            let operations = node
+                .context
+                .store
+                .get_operations_by_document_id(document_id)
+                .await
+                .unwrap();
+
+            // Build the document from the operations.
+            let document_builder = DocumentBuilder::from(&operations);
+            let document = document_builder.build().unwrap();
+
+            // Issue a reduce task for the document, which also inserts the current view.
+            let input = TaskInput::new(Some(document_id.to_owned()), None);
+            assert!(reduce_task(node.context.clone(), input).await.is_ok());
+
+            // Issue a reduce task for the document view, which should succeed although no new
+            // view is inserted.
+            let input = TaskInput::new(None, Some(document.view_id().to_owned()));
+            assert!(reduce_task(node.context.clone(), input).await.is_ok());
+        })
+    }
 }