Most likely, yes. In Oregon, one of the sides must request the witness exclusion rule. It doesn't just happen automatically. But if you have been told by the prosecution that you will be excluded, you can pretty much bet that the prosecutor will request the exclusion.

Especially if you are a hostile witness. What the prosecution will want to avoid is your watching any testimony, and then tailoring your testimony to undermine their case. They want you to testify without any knowledge of what any other witness said. If your story is contradicts other witness' stories, it won't be because you listened to what they said, and changed anything. It will just have happened based on your differing recollections.