What kind if tense is had had or 'd had

[Unregistered]

I came across it while I was reading a book

He had had two houses.

[izabela]

Past Perfect

HAD + PAST PARTICIPLE

It just happens that the past participle of have is had, hence He had had two houses

The Past Perfect expresses the idea that something occurred before another action in the past. It can also show that something happened before a specific time in the past.

I hope it helps