Lars Andersson Luckarin - ?

I don't understand the question. If somebody have stepbrother or stepsister,they must have same father or same mother. If you mean, that word step means same as word foster (child), it is bossible, but very unlikely. Lauri Lukkarinen and his wife arrived to marry from different villages and both have own known parents.
Hannu.

Lars Andersson Luckarin's (Lauri Antinpoika Lukkarinen) wife was Walborg Andersdotter Pynnöin (Valpuri Antintytär Pynnönen). They were married on 31.11.1706.

Lars' father was Anders Luckarin (Antti Lukkarinen) and mother was Karin/Carin Laitin (Kaarina/Katariina ANTINTytär Laitinen), born circa 1665.
Walborg's father was Anders Pynnöin (Antti Pynnönen) and mother Carin Mattsdotter Laitin (Kaarina/Kaisa MATINtytär Laitinen) birth circa 1667.

Lars' mother Carin's father was Anders Laitin (Antti Laitinen) and
Walborg's mother Carin's father was Mats Laitin (Matti Laitinen)

So Lars didn't marry his stepsister.