did you order them from the site or via the kickstarter because if you filled out the form from the kickstarter then your order didn't actually process because they found out that the form cant handle the data properly and are instead having an application built to do all the ks ordering on.
if you ordered it via the site you can probably contact their support and get the order changed.

i ordered nothing yet, i payed on kickstarter for these 2 heroes but haven't got yet any form to fill out. So it is a fact that these are just variant minis , right?

PS - look in the "big heroes" table on kickstarter Everassur is NOT a unique character, while immortal is. Maybe they are not the same at all? Who at all thought it up? is there any link from Prodos stating that?

Why should they be just mini variants? I see no reason for that notion.
Moreover, if you look at the unit classification chart (KS main page), you will notice that the Immortal is a unique hero, while the Everassur is a non-unique hero. So if this chart is legit (and there's no reason to think otherwise), they are clearly different heroes.
Besides, I cannot find any info by Prodos hinting on them being just variants.

Update: Prodos cleared it up on the KS comments section: Immortal and Everassur are completely different models with completely different rules, and you can field 1 Immortal and 2 Everassurs at the same time, if you like.