Just out of curiosity are there any professional programmers out there who don't regularly copy functions from the Internet?
Part of being a contemporary coder is making use of available code. Libraries of functions are "other people's code". Languages are other people's code. Etc. it's all about other people's code.
This defense always comes up when cheating is the issue, and it is always wrong. The purpose of an examination is to determine if an individual understands the subject matter, and no argument how programming is done in practice alters the fact that a cheater has failed to demonstrate that he understands the subject matter (and has, in fact, provided good evidence that he does not.)
Furthermore, one should not be spending the time and money a degree from Duke costs, just to be a cut-and-paste coder - a semester at a community college should be enough, if you can't teach yourself. The purpose of a university education is to develop a thorough understanding of the subject matter in order to become the person who finds solutions to problems, rather than the people who copy them.