Redstone dust does not work right! (look screenshot)

Hi....
Today I made me a own calculator in Minecraft.... But then i saw a inconsestent result of my input ... so i checked every single redstone of my calculator and found this:

And that was not just one redstone dust which was so ... thught "hmmm maybe a bug that never will hapen again" and BAM i saw a second one .... but destroyed the first one without making a screenshot ._.