I'm trying to get both the Irreplaceable You and Special Assignment achievements, but am stuck with the last two, Hyadures and Phyneus the Growler. According to Where do the Act 5 Unique monsters spawn for the Special Assignment / Irreplaceable You achievements? (and other references), I should look in Pandemonium Fortress level 1 for Hyadures and in Westmarch Commons for Phyneus.
However, other uniques can also spawn in those areas, so I want to know whether, if I should find either Captain Gerber or Dale Hawthorne, I should abandon the search in Westmarch for Phyneus or whether they can spawn in the same area in the same game?
And the same with Hyadures and, say, Razael or Lograth?