The kit is quite comprehensive, with really clean, pre-finished castings. My only quibble (aside from the fluorescent orange barn roof) is the telephone poles: they seem a bit tall. I also don't ever recall seeing poles with crossarms on both sides. Not saying they don't exist, I've simply never seen any like that.
I wish the Atlas telephone poles were this long as I like to just poke them into foam and after clipping the base off and doing just that, they get pretty short. These have enough pole to plant in the foam and still cover the 15'-50' range that poles run. 15' in open fields, more height when crossing roads/tracks/other pole lines/etc. as needed.
As for the double arms, that wasn't usually done on the whole pole line, just for extra bracing. Pole arms should alternate front-back-front as the pole line is run, to spread the force of a pulled wire. I assume then that a double arm pole was used when that pattern didn't match as a pole line came together from two ends.
I think Gordon Odegard covered some of this in an old MR article.