Question about a programme

On page 194 of "Effective AWK programming" we see the
following programme:

# rewind.awk --- rewind the current file and start over
function rewind(    i)
{
    # shift remaining arguments up
    for (i = ARGC; i > ARGIND; i--)
        ARGV[i] = ARGV[i-1]
    # make sure gawk knows to keep going
    ARGC++
    # make current file next to get done
    ARGV[ARGIND+1] = FILENAME
    # do it
    nextfile
}

Isn't the statement ARGV[ARGIND+1] = FILENAME
superfluous ? In the loop when i gets the
value ARGIND + 1 then the assignment
ARGV[ARGIND + 1] = ARGV[ARGIND] will be executed
and ARGV[ARGIND] always has the same value as
FILENAME