I don’t remember ever seeing multiple dovs. (I’ve been playing since the Petri Dish dynasty.)

I’m sure we’ve had few that have failed before, making more than one per dynasty, but don’t recall when.

We’ve never had any simultaneously pending ones before, though - it’s been assumed that only one can be made at a time, in the past.

I recall one made during Hiatus before.  I can’t recall when, but I think it was Excalibur.

We had almost multiple DoV during aaron dynsaty.

We had multiple DOVs when I won my second dynasty. (Smith tried to steal, if I recall correctly.)