I also have 2 copies of the cards you mentioned. I can't disenchant Altrius or Nethrandamus but I could disenchant the extra old murk eye. Also after disenchanting things manually the crafting button is animated but when I click on it there is nothing to disenchant.
Those portraits 'out of nowhere' are there because Arena now also counts towards progression. Probably other stuff that they haven't divulged yet in previous statements on such short notice -or that they aren't even aware of, which is completely plausible because this is Blizzard/Activision we are talking about. Such is the state of the company that the journos find out about people getting fired before the ones that get fired even learn about it. No laughing matter but it is kind of funny in a way.
The game is buggy as expected; it sometimes gives blank warnings, some cards straight up disappear from the collection and menu buttons start to glow spontaneously in-between matches or navigating through menus. Some of the adventures I've finished also started to glow. Haven't checked the progression tab, so it likely is a visual bug. I think it is safe to diss the second Murk Eye.
I'm digressing here a bit but they decided that Wyrm Weaver wasn't eligible for a dust refund. Although the cost was reduced, the combined stats are also reduced in the process. Unintuitive, nonsensical; so Blizzard-like.