The blood type is a question of proteins. Yes, human blood looks the same with you and me, but it is probably different, if we aren't related. And if they are different, and some of my blood gets into your blood, the result is heavy immune defence and you get sick. But there are systems to look if they match closely, then the rejection isn't so strong.
And yup, I believe yautjas have different blood types 'cos they are individuals and they prolly have biological reorganizing, cross-overs, mutation etc. biological methods to make them as individuals. And this affects to proteins (in the blood). But I don't know what kind of system they have to inherit the genetic information, hmmmh... Triple DNA? lol
Ok, I bet some of you are lost so I'll stop lol But it is hard to say anything about imagined creature from outer space.
The servant and the observer of Balatu
Kingdom of Predators