With this approach, the application may receive a duplicate message after a broken connection, but it will not lose any.

使用此方法，应用程序可以在断开连接后接收重复的消息，而不会丢失任何内容。

youdao

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

For example, if a duplicate source table row matches exactly with the same target table row that has been updated, you will see the error message.

例如，如果复制已被更新的、与相同目标表行匹配的源表行，那么您将会看到错误消息。

youdao

Some Tumblr users are seeing their pages replaced with several dozen duplicate posts from a known hacker group, warning that deleting said message will delete the Tumblr page in question (it's unclear if this is actually true, but seems to be false in our testing).

ENGADGET: Hacker group rewriting Tumblr pages into a racist, anti-gay screed (update: Tumblr says it's fixed)