Yes, certainly.

If you copy the input from the stdin through a pipe, that's trivially less efficent than if you dupe the filehandle. In the second case, the new program just reads directly from whatever file stdin was connected to. With a pipe, you need a separate process that has to copy data from stdin to the pipe every time the second program needs data; under linux a pipe has a buffer of length 4096 by default, so the os has to do a task switch to the first process and back to the second one for every 4K bytes read (it is possible that some of the overhead can be avoided with the sendfile syscall). Also, the first process occupies memory and a process table entry. In addittion, you have to take care not to block data with too much buffering; also the pipe solution might not even work on win32.