diff --git a/crates/apub/src/activities/community/announce.rs b/crates/apub/src/activities/community/announce.rs
index 0ece90b76..5bfcb9317 100644
--- a/crates/apub/src/activities/community/announce.rs
+++ b/crates/apub/src/activities/community/announce.rs
@@ -14,6 +14,7 @@ use lemmy_apub_lib::{
 };
 use lemmy_utils::LemmyError;
 use lemmy_websocket::LemmyContext;
+use tracing::debug;
 
 #[async_trait::async_trait(?Send)]
 pub(crate) trait GetCommunity {
@@ -113,7 +114,15 @@ impl ActivityHandler for AnnounceActivity {
         let object_value = serde_json::to_value(&self.object)?;
         let object_data: ActivityCommonFields = serde_json::from_value(object_value.to_owned())?;
 
-        insert_activity(&object_data.id, object_value, false, true, context.pool()).await?;
+        let insert =
+          insert_activity(&object_data.id, object_value, false, true, context.pool()).await?;
+        if !insert {
+          debug!(
+            "Received duplicate activity in announce {}",
+            object_data.id.to_string()
+          );
+          return Ok(());
+        }
       }
     }
     self.object.receive(context, request_counter).await
diff --git a/crates/apub/src/http/mod.rs b/crates/apub/src/http/mod.rs
index 3328e509d..477357e04 100644
--- a/crates/apub/src/http/mod.rs
+++ b/crates/apub/src/http/mod.rs
@@ -28,7 +28,7 @@ use lemmy_utils::{location_info, LemmyError};
 use lemmy_websocket::LemmyContext;
 use serde::{Deserialize, Serialize};
 use std::{fmt::Debug, io::Read};
-use tracing::info;
+use tracing::{debug, info};
 use url::Url;
 
 mod comment;
@@ -108,7 +108,15 @@ where
   // Log the activity, so we avoid receiving and parsing it twice. Note that this could still happen
   // if we receive the same activity twice in very quick succession.
   let object_value = serde_json::to_value(&activity)?;
-  insert_activity(&activity_data.id, object_value, false, true, context.pool()).await?;
+  let insert =
+    insert_activity(&activity_data.id, object_value, false, true, context.pool()).await?;
+  if !insert {
+    debug!(
+      "Received duplicate activity {}",
+      activity_data.id.to_string()
+    );
+    return Ok(HttpResponse::BadRequest().finish());
+  }
 
   info!("Receiving activity {}", activity_data.id.to_string());
   activity
diff --git a/crates/apub/src/lib.rs b/crates/apub/src/lib.rs
index b540ac2ba..7a66e8aa2 100644
--- a/crates/apub/src/lib.rs
+++ b/crates/apub/src/lib.rs
@@ -201,11 +201,12 @@ async fn insert_activity(
   local: bool,
   sensitive: bool,
   pool: &DbPool,
-) -> Result<(), LemmyError> {
+) -> Result<bool, LemmyError> {
   let ap_id = ap_id.to_owned().into();
-  blocking(pool, move |conn| {
-    Activity::insert(conn, ap_id, activity, local, sensitive)
-  })
-  .await??;
-  Ok(())
+  Ok(
+    blocking(pool, move |conn| {
+      Activity::insert(conn, ap_id, activity, local, sensitive)
+    })
+    .await??,
+  )
 }
diff --git a/crates/db_schema/src/impls/activity.rs b/crates/db_schema/src/impls/activity.rs
index d946d628f..261a89cbe 100644
--- a/crates/db_schema/src/impls/activity.rs
+++ b/crates/db_schema/src/impls/activity.rs
@@ -1,7 +1,10 @@
 use crate::{newtypes::DbUrl, source::activity::*, traits::Crud};
-use diesel::{dsl::*, result::Error, *};
+use diesel::{
+  dsl::*,
+  result::{DatabaseErrorKind, Error},
+  *,
+};
 use serde_json::Value;
-use std::io::{Error as IoError, ErrorKind};
 
 impl Crud for Activity {
   type Form = ActivityForm;
@@ -35,13 +38,14 @@ impl Crud for Activity {
 }
 
 impl Activity {
+  /// Returns true if the insert was successful
   pub fn insert(
     conn: &PgConnection,
     ap_id: DbUrl,
     data: Value,
     local: bool,
     sensitive: bool,
-  ) -> Result<Activity, IoError> {
+  ) -> Result<bool, Error> {
     let activity_form = ActivityForm {
       ap_id,
       data,
@@ -49,13 +53,14 @@ impl Activity {
       sensitive,
       updated: None,
     };
-    let result = Activity::create(conn, &activity_form);
-    match result {
-      Ok(s) => Ok(s),
-      Err(e) => Err(IoError::new(
-        ErrorKind::Other,
-        format!("Failed to insert activity into database: {}", e),
-      )),
+    match Activity::create(conn, &activity_form) {
+      Ok(_) => Ok(true),
+      Err(e) => {
+        if let Error::DatabaseError(DatabaseErrorKind::UniqueViolation, _) = e {
+          return Ok(false);
+        }
+        Err(e)
+      }
     }
   }