X509CRL AuthorityKeyIdentifier Extension

I have a List of X509CRLs and I want to get through it and get certain CRL's. I was doing it using issuer field:

for(var crl: List<X509CRL> crls){
 String issuer = c.getIssuerX500Principal().getName();
 if(issuer.contains("searchString"))
  result.add(crl);
}

But I digged into it a little deeper and found out that there are certain Extensions in the CRL's I'm parsing and one of them named AuthorityKeyIdentifier. I was able to parse and get it in my JAVA code, it's not the problem, the problem is that I've read about it a little, but couldn't understand, can I use it as something to determine the CRL? So can someone answer to these 2 questions about this extension:

1. Is it unique for the each CRL file?
2. If it's not, can it be at least guaranteed that CRL's with the same AuthorityKeyIdentifier extension are from the same UC/CA (or whatever it's called)?