Hello Nico,
thanks for answer!
Actualy I would include it as snippet.
So, are you suggesting, that when I use template() it should be something like this:
<?php foreach(page()->children()->template(template-a) as $page): ?>
...
<?php endforeach ?>
then
<?php foreach(page()->children()->template(template-b) as $page): ?>
...
<?php endforeach ?>
I am pretty sure I did it wrong because it’s not working 
but how to use it right?