print only last matched line

[tester_V]

Greetings!
I'm having a hard time with this problem.
I need to print only the last match of "second line" for each "first line".

The output should look like this:

First line, second line
First line, second line

Here is a kind of example of a file:

some lines here
some lines here and more
first line to find --InitializeRequest more stuff
some lines here
some lines here and more
second line to find --LotComplete some stuff here
second line to find --LotComplete some stuff here
some lines here
some lines here and more
first line to find --InitializeRequest more stuff
some lines here
some line here and more
second line to find --LotComplete some stuff here
second line to find --LotComplete some stuff here
second line to find --LotComplete some stuff here
second line to find --LotComplete some stuff here
second line to find --LotComplete some stuff here
second line to find --LotComplete some stuff here
some lines here
some lines here and more
first line to find --InitializeRequest more stuff
some lines here
some line here and more
second lines to find --LotComplete some stuff here
second lines to find --LotComplete some stuff here
second lines to find --LotComplete some stuff here
some lines here
some lines here and more
first line to find --InitializeRequest more stuff
some lines here
some lines here and more
second line to find --LotComplete some stuff here

Thank you.