Page 265 of the Collins English Usage reads
If one of a series of events is happening now or has just happened, you refer to it as the latest one.
You refer to the event before the latest one as the last one. If no event of the kind you are talking about has happened recently, you refer to the most recent one as the last one.
If someone keeps having or producing a series of things, you refer to the one they have now or the one they have produced most recently as their latest one.
You refer to the one before their latest one as their last one. If they have not had or produced one recently, you refer to their most recent one as their last one.
I do not understand the use of the last for the one before the latest one, and unfortunately no example is given for it.