about Mercenaries Skills

in the poe.db
https://poedb.tw/us/Mercenaries#Builds

Skills are divided into three categories: Primary, Secondary and Utility. Select up to two skills from each category.

but the Eruptor has three skills from Primary

I experience the same with eruptor merc.

I have seen other mercs that have had 3 primary skills before (I believe sanguinemancer), BUT eruptor is the only one ive seen that always rolls 3 primary skills. I have yet to see one with more than 1 utility skill, but have seen quite a few others.