It's interesting. In this case, 前 have two meanings "opposite side" and "in front of" Therefor,その時、太郎は、店の前の前にみかんが一つ置いてあるのを見た。 ⇒Tarou saw a orange which is being put in front of shop on opposite side. But it's also possible this meaning. ⇒Tarou saw a orange which is being put in front of forward of shop. Of course this is quite weird. I hope this answer will help you.