There is always more to the error message than the final two lines you posted. In the IDE, there is a copy button that will copy the entire error message that you can then post here, inside code tags which would be more helpful.
Not sure what you mean by getting added wtice since it is in his code? The entire library? just a reference to the library with #include? Posting the code here would be helpful.
All these topics are covered here to help you get the most out of these forums: How to get the best out of this forum - Using Arduino / Installation & Troubleshooting - Arduino Forum
It is worth the 10 minute read.