Never seen this in my ~500hrs of play. Is this a bug or did I get lucky?
No bug, one is from the MI, the other from the affix.
Now attach a weapon component to it and get a 3rd skill.
If you want something really impressive, you can actually get an item with 2 of the same skill innately. Gerthard’s Keeper’s Buckler both come with an innate on-block ability, and this same on-block ability is able to come from a rare suffix.
This means you can get two separate instances of this ability to proc from the same item.
However, an item cant get 2 skills from prefix and suffix (even if it rolls corresponding mods). One of the abilities will be wasted.