aspd and other disorders coexisting

I need some insight on this, I want to know if aspd could coexist with disorders such as multiple personality disorders or split personality disorders(I really forgot the name, sorry lol) I'm writing a character that is supposed to struggle with these disorder and I'd like to make it realistic. I wouldn't say it's exactly aspd I wrote the character with but more so apathy, though he does have psychopathic tendencies. please someone tell me if this is bs or could it actually exist together?