That’s because those templates don’t support those aliases and IABot knows it.

Ah makes sense. Any chance IABot could remove the prior arguments to avoid duplicates? That's what I've been doing with Medic but removing them manually as there are too many weird cases that show up (unrelated to IAbot).

Unfortunately, as a consequence of the new engine, if they aren’t supported, IABot will not acknowledge them.

Would it be reliable to say when IABot adds new arguments they are at the end of the citation ie. the archiveurl/archivedate that come first can be deleted?

Yes.

This bug is active. Testcases:

https://en.wikipedia.org/w/index.php?title=User%3AGreenC%2Ftestcases%2FT205623&type=revision&diff=867716886&oldid=867716846