diff --git a/addons/mail/models/discuss/discuss_channel.py b/addons/mail/models/discuss/discuss_channel.py
index 23854c26aab..bf6dbe7771c 100644
--- a/addons/mail/models/discuss/discuss_channel.py
+++ b/addons/mail/models/discuss/discuss_channel.py
@@ -1109,6 +1109,7 @@ class Channel(models.Model):
             :returns: channel_info of the created channel
             :rtype: dict
         """
+        partners_to = set(partners_to)
         channel = self.create({
             'channel_member_ids': [Command.create({'partner_id': partner_id}) for partner_id in partners_to],
             'channel_type': 'group',