Local messages have an impact on the performance of our system. It is best when messages are as much as possible part of the system messages. In order to remove unnecessary duplication, all the messages that have a local  localisation and are exactly the same as the system message will be removed. What we ask you to do is to compare and proof read the messages in translatewiki.net and the local messages. You can then either remove local messages when the translatewiki.net message is to be preferred or, you can update the message at translatewiki.net.