if there are two voltaic servant triggers, can i respond to the second trigger after the first trigger resolves? For example; I tap steel overseer during my turn. At the end of my turn my two voltaic servants trigger to untap a target artifact. I untap my steel overseer for the first trigger and in response to the second trigger I tap steel overseer again. After that the second trigger goes off and I will have effectively tapped steel overseer 2 times and untapped 3 times because of the two voltaic servants. Is this correct?
Yes, this is correct.
Rule 117.1b states:
117.1b A player may activate an activated ability any time they have priority.
And rule 117.3b states:
117.3b The active player receives priority after a spell or ability (other than a mana ability) resolves.
Based on that, you will receive priority after the first trigger resolves, and may activate Steel Overseer's ability, putting it on the stack. After that resolves and each player passes priority, the Voltaic Servant's ability still on the stack resolves normally, untapping target artifact.