That's odd... they DO spawn together, or at least, they're supposed to. I wonder how they got lost. Does his link say it's impossible, or does it just say you need to defeat Mordecai? If it's the latter, Mordecai should be somewhere, but I have no idea how they got separated like that. He's had a lot of notable encounters too, the other guys have posted about it frequently so it usually has been working. Hmm. I'll look into it though. Thanks.
I guess they got separated after I retreated around a corner into a narrow corridor. I didn't see any Mordecai, but then he showed up in 2 turns after I had killed Reprobus.