I have studied numbers of errors caused by using the Copy-Paste method and can assure you that programmers most often tend to make mistakes in the last fragment of a homogeneous code block. I have never seen this phenomenon described in books on programming, so I decided to write about it myself. I called it the "last line effect".
I have unintentionally raised a large debate recently concerning the question if it is legal in C/C++ to use the &P->m_foo expression with P being a null pointer. The programmers' community divided into two camps. The first claimed with confidence that it wasn't legal while the others were as sure saying that it was. Both parties gave various arguments and links, and it occurred to me at some point that I had to make things clear. For that purpose, I contacted Microsoft MVP experts and Visual C++ Microsoft development team communicating through a closed mailing list.