Schizotypal and borderline personality disprder - can it be possible to have both?

Yes: Personality disorders are not necessarily mutually exclusive. It is possible to have more than one. There is evidence that schizotypal personality disorder may be more likely genetically inherited then borderline personality disorder. Borderline personality disorder on the other hand often has its origins in early childhood trauma neglect or abandonment.

Possible not likely: Anything is possible in the human condition, but to have both of these co-occurring is quite unlikely. A full psychiatric evaluation is vigorously indicated to differentiate symptoms.