There is nothing wrong with that app and it won't hurt your computer. The app is correct and Mavericks is fudging the percent readout.
Code:ioreg -w0 -l | grep Capacity
Run this command in Terminal and you will see the output (straight from the OS) matches exactly what is shown in Coconut battery. If you do the math on the output for current vs max (7292/7395 = .986 ~99% in my case) you will see it matches Coconut battery also. I have done this before at lower charge levels of around 80% and it still holds true. Coconut matches the Terminal output and is accurate.
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Excellent cmd line info!!!