Bipolar disorder and Borderline Personality Disorder are not the same illnesses. If you have been diagnosed by a psychiatrist with both of these disorders than it is called a Dual Diagnosis. Some symptoms or signs of Bipolar are relative to BPD however, with BPD there are over 7 clinical criteria that has to be met before a firm diagnosis can be obtained. I would suggest speaking to your physician about
your concerns of this other diagnosis and seeing what they think. Take care