Likewise, the receiving side must not only agree to send back an ack once they receive a message, but they must ignore any duplicate messages.

同样，接收方不仅要同意一旦收到消息，立刻返回一个ack，还必须忽略任何重复的消息。

youdao

We understand that this news must be disappointing to receive and, for that reason, we will not send a duplicate notification of this decision by mail.

那啥，我知道这消息很让人失望，所以，我们就不再刺激你了，你不会再收到纸质通知的。

youdao