You randomly get 1 or 2 skillpoints at each lvl-up...
I always save just before lvling, and within 10 reloads I always get 2 pts for my hero & 2 for DK... 4 skillpoints every lvl.
When I finished the game the first time, I had hardly used the dolls...
This time I'm really using them... the extra skillpoints come in handy...
...I put the initial 2 skillpoints the first doll has into lvl-upgrade -> level 5 summonong doll. Something went 'wrong' here, because after the upgrade, my doll was permanent (ould go to other rooms, even teleport to battlefields). Even if it died and was summoned again, it went anywhere.
Too bad that effect has gone in Act2...