Can Dissociative identity disorder and Borderline Personality Disorder seem similar?

It is possible to have both DID and BPD. Sometimes patients who have DID are misdiagnosed several times b4 they are correctly dx'd as having DID. BPD is more about failure to be able to regulate emotions, and many with BPD do have a traumatic history. DID is more about the time loss and confusion and trauma and being more than one person inside of only one body. Most people do not meet ALL of the requirements of any diagnosable mental illness- and may have a few characteristics of one issue and a few characteristics of another and another-- you are dx'd based on your behavior and how you answer questions and how you describe symptoms. It is based on how you portray yourself to be in front of them. Try the treatment for BPD (which is usually DBT, therapy, and medicine). If it doesn't work, it's time to try something else, that's all. One step at a time.