Two reasons why you might want to say something twice.
1) It might be that although people have heard it before, it's really important that they hear it again.
Maybe they didn't understand the first time or weren't listening properly.
2) Maybe because you said it before, it doesn't mean they heard it before. Maybe you should say it twice because you're speaking to different people. They've never heard what you've got to say, and it's important that they hear it.
Just because you have heard yourself say it before doesn't mean it's not worth saying again.
Better to understand that everyone is busy, and if your message is important enough, it's worth the effort to repeat it.
Blog Post Number - 3730