Not really close, it’s the same satellites and channels as you get on a Sky box. Freesat is just an epg (electronic programme guide) service (an alternative to the Sky one). You have two cables because the previous tenant had a twin tuner box. Connect either one.
You could use the other cable for a 2nd HB1000S if you wanted.
There is a very small possibility that has only recently become a possibility. If the previous tenant had SKy Q they may have left a non standard lnb on the dish. Sky Q uses a different design wideband lnb.
It is however a very quick and cheap job to change the lnb for a standard universal Sky type lnb.