If my memory serves me correctly.....
I know the Steelers logo was a steel company logo in Pittsburgh. The diamonds are the molecular diagram of steel.
Now, the reason for only 1 sticker is........The team equipment manager counted 75 helmets, thus he ordered 75 decals. Found out that he should have doubled the number of stickers for "both" sides. The team owner said, finish it off, we have a game tomorrow. Well, the Steelers won, the players said the stickers were good luck that way so don't bother putting them on the other side.
BTW.......I love this kind of stuff........There is history behind this, the team uniforms, team names, colors, ect.