BPD does have dissociation as a symptom for some, but it doesn't mean there is co-existing DID either or a separate dissociative disorder. it all depends on the person.

the type of dissociation in BPD is where you can forget what you did, but it doesn't mean you have an alter as dissociation can affect your memory in general since it tends to blow circuits in your brain (or so that's how i describe it). in BPD, it is usually triggered (like the other well known forms of dissociation) from stress and overwhelming feelings and the whole dysregulation aspect/not being able to soothe/calm yourself, etc.

i was reading up on that to try to figure out the difference as i have variations of dissociation which was why i was confused what 'might' be related to BPD, DID, or maybe even on its own.