Select 2 categories in Hikashop content module

Hi,

There is no option to do that.
What you could do is to create a category "rock records" (unpublished if you don't want it to appear on the frontend). Then, you can create a mass action with two filters on the category, one for rock, one for records, and an action to add the "rock records" category. When you process the mass action, the products which are in both categories will be added to that third category.
That way, if you create a module for that category only the products you want will be listed in it.