To answer the question yes they do stack if you have 3 of these out and you play apillar then you will get 3 Golems in play.
I'm sorry zac3333 I was unaware you had a card with a similar name. Any chance of a link?
To answer the OP debate, i am unsure if this is OP. Like already stated it depends on the amount of pillars played out and if your opponent waits and steals it fromyou then hey it is there gain. If you plan on saying it is OP then please inform me in which way you mean so I can taylor a solution to this.
Thanks
Scyther