mixed cabbage seed

being my first year i bought one pack of cabbage seed    (variety is hispie)  planted out and have harvested 12 lovely cabbies  they are now in the freezer
five weeks late i seeded and planted out 12 more now for the life of me they are defo not the same variety they look nothing like the 1st batch is it possible to get a packet of mixed seeds  :blink: the 2nd batch are coming on a treat and they are gonna be stunners i hope

i must be going mad im off to check my seed box for the umpteenth time

your thoughts please 

Could it be the difference in weather conditions? Different soil? Grown in more/less light?
As you say it's a weird one.....