This is indeed an odd but very common verb structure in contemporary English. It is used when the speaker wants to say that an action surpassed a threshold of some kind. In register, it is conversational, not formal.
My dog chewed up my homework.
-- Looks like he more than chewed it up. He appears to have devoured it! Where is it?
That is, He did more than chew it up, he devoured it.
Notice that the tense is simple past without auxiliary in more than chewed. Rather than an omission of the auxiliary, this construction is an alternative to it.
Your work has more than met our expectations. It has surpassed them.
She more than won the race—she set a world record.
You more than passed the course you were failing early in the semester; you aced the final exam.
The construction appears also with other tenses.
With rising electricity costs, these solar panels will more than pay for themselves after ten years.
That is, they will have done more than pay for themselves after ten years; their initial acquisition cost will already have been offset by savings on your electricity bills, and thenceforward all of the savings on the energy bill will go directly into your pocket.