diff --git a/js/modules/data.d.ts b/js/modules/data.d.ts
index 35a87b0f5..17ac87ebc 100644
--- a/js/modules/data.d.ts
+++ b/js/modules/data.d.ts
@@ -267,6 +267,10 @@ export function getMessageBySender(
   }: { source: any; sourceDevice: any; sent_at: any },
   { Message }: { Message: any }
 ): Promise<any>;
+export function getMessagesBySender(
+  { source, sourceDevice }: { source: any; sourceDevice: any },
+  { Message }: { Message: any }
+): Promise<Whisper.MessageCollection>;
 export function getMessageIdsFromServerIds(
   serverIds: any,
   conversationId: any
diff --git a/js/modules/data.js b/js/modules/data.js
index e532978e1..6de00db8c 100644
--- a/js/modules/data.js
+++ b/js/modules/data.js
@@ -151,6 +151,7 @@ module.exports = {
   removeAllMessagesInConversation,
 
   getMessageBySender,
+  getMessagesBySender,
   getMessageIdsFromServerIds,
   getMessageById,
   getAllMessages,
@@ -1015,6 +1016,23 @@ async function getMessageBySender(
   return new Message(messages[0]);
 }
 
+async function getMessagesBySender(
+  // eslint-disable-next-line camelcase
+  { source, sourceDevice, sent_at },
+  { Message }
+) {
+  const messages = await channels.getMessageBySender({
+    source,
+    sourceDevice,
+    sent_at,
+  });
+  if (!messages || !messages.length) {
+    return null;
+  }
+
+  return messages.map(m => new Message(m));
+}
+
 async function getUnreadByConversation(conversationId, { MessageCollection }) {
   const messages = await channels.getUnreadByConversation(conversationId);
   return new MessageCollection(messages);
diff --git a/js/modules/loki_app_dot_net_api.js b/js/modules/loki_app_dot_net_api.js
index ae606fb35..369de615a 100644
--- a/js/modules/loki_app_dot_net_api.js
+++ b/js/modules/loki_app_dot_net_api.js
@@ -6,13 +6,13 @@ const { URL, URLSearchParams } = require('url');
 const FormData = require('form-data');
 const https = require('https');
 const path = require('path');
+const dataMessage = require('../../ts/receiver/dataMessage');
 
 // Can't be less than 1200 if we have unauth'd requests
 const PUBLICCHAT_MSG_POLL_EVERY = 1.5 * 1000; // 1.5s
 const PUBLICCHAT_CHAN_POLL_EVERY = 20 * 1000; // 20s
 const PUBLICCHAT_DELETION_POLL_EVERY = 5 * 1000; // 5s
 const PUBLICCHAT_MOD_POLL_EVERY = 30 * 1000; // 30s
-const PUBLICCHAT_MIN_TIME_BETWEEN_DUPLICATE_MESSAGES = 10 * 1000; // 10s
 
 // FIXME: replace with something on urlPubkeyMap...
 const FILESERVER_HOSTS = [
@@ -1799,7 +1799,7 @@ class LokiPublicChannelAPI {
     }
 
     return {
-      timestamp,
+      timestamp: new Date(`${adnMessage.created_at}`).getTime() || timestamp,
       attachments,
       preview,
       quote,
@@ -1913,7 +1913,10 @@ class LokiPublicChannelAPI {
         if (messengerData === false) {
           return false;
         }
-
+        // eslint-disable-next-line no-param-reassign
+        adnMessage.timestamp = messengerData.timestamp;
+        // eslint-disable-next-line no-param-reassign
+        adnMessage.body = messengerData.text;
         const {
           timestamp,
           quote,
@@ -1927,20 +1930,15 @@ class LokiPublicChannelAPI {
         }
 
         // Duplicate check
-        const isDuplicate = message => {
-          // The username in this case is the users pubKey
-          const sameUsername = message.username === pubKey;
-          const sameText = message.text === adnMessage.text;
-          // Don't filter out messages that are too far apart from each other
-          const timestampsSimilar =
-            Math.abs(message.timestamp - timestamp) <=
-            PUBLICCHAT_MIN_TIME_BETWEEN_DUPLICATE_MESSAGES;
-
-          return sameUsername && sameText && timestampsSimilar;
-        };
+        const isDuplicate = (message, testedMessage) =>
+          dataMessage.isDuplicate(
+            message,
+            testedMessage,
+            testedMessage.user.username
+          );
 
         // Filter out any messages that we got previously
-        if (this.lastMessagesCache.some(isDuplicate)) {
+        if (this.lastMessagesCache.some(m => isDuplicate(m, adnMessage))) {
           return false; // Duplicate message
         }
 
@@ -1949,9 +1947,11 @@ class LokiPublicChannelAPI {
         this.lastMessagesCache = [
           ...this.lastMessagesCache,
           {
-            username: pubKey,
-            text: adnMessage.text,
-            timestamp,
+            propsForMessage: {
+              authorPhoneNumber: pubKey,
+              text: adnMessage.text,
+              timestamp,
+            },
           },
         ].splice(-5);
 
diff --git a/ts/receiver/dataMessage.ts b/ts/receiver/dataMessage.ts
index dddde9cfb..971d4ccc3 100644
--- a/ts/receiver/dataMessage.ts
+++ b/ts/receiver/dataMessage.ts
@@ -356,30 +356,49 @@ interface MessageId {
   source: any;
   sourceDevice: any;
   timestamp: any;
+  message: any;
 }
+const PUBLICCHAT_MIN_TIME_BETWEEN_DUPLICATE_MESSAGES = 10 * 1000; // 10s
 
 async function isMessageDuplicate({
   source,
   sourceDevice,
   timestamp,
+  message,
 }: MessageId) {
   const { Errors } = window.Signal.Types;
 
   try {
-    const result = await window.Signal.Data.getMessageBySender(
-      { source, sourceDevice, sent_at: timestamp },
+    const result = await window.Signal.Data.getMessagesBySender(
+      { source, sourceDevice },
       {
         Message: window.Whisper.Message,
       }
     );
+    if (!result) {
+      return false;
+    }
 
-    return Boolean(result);
+    const isSimilar = result.some((m: any) => isDuplicate(m, message, source));
+    return isSimilar;
   } catch (error) {
     window.log.error('isMessageDuplicate error:', Errors.toLogFormat(error));
     return false;
   }
 }
 
+export const isDuplicate = (m: any, testedMessage: any, source: string) => {
+  // The username in this case is the users pubKey
+  const sameUsername = m.propsForMessage.authorPhoneNumber === source;
+  const sameText = m.propsForMessage.text === testedMessage.body;
+  // Don't filter out messages that are too far apart from each other
+  const timestampsSimilar =
+    Math.abs(m.propsForMessage.timestamp - testedMessage.timestamp) <=
+    PUBLICCHAT_MIN_TIME_BETWEEN_DUPLICATE_MESSAGES;
+
+  return sameUsername && sameText && timestampsSimilar;
+};
+
 async function handleProfileUpdate(
   profileKeyBuffer: Uint8Array,
   convoId: string,
@@ -588,9 +607,7 @@ export async function handleMessageEvent(event: MessageEvent): Promise<void> {
   // if the message is `sent` (from secondary device) we have to set the sender manually... (at least for now)
   source = source || msg.get('source');
 
-  const isDuplicate = await isMessageDuplicate(data);
-
-  if (isDuplicate) {
+  if (await isMessageDuplicate(data)) {
     // RSS expects duplicates, so squelch log
     if (!source.match(/^rss:/)) {
       window.log.warn('Received duplicate message', msg.idForLogging());