I’ll link it here, especially for all the… ‘skeptical’ people and exceptionally skilled readers:
See also my comment below there: 25.4.1 Patch Notes - #17 by SparkyElf-2852 .
So yeah, a reroll is supposed to be offered for Loatheb, among others, too, although the questionability of such functionality in general has been debated already (above in this topic, for instance) — why would someone want to reroll one ‘duplicate’ legendary to another, just duplicate, I dunno.