awk '
NF > 0 {
    if ($1 == lastword)
        printf("double %s, line %d\n", $1, NR)
    for (i = 2; i <= NF; i++)
        if ($i == $(i-1))
            printf("double %s, line %d\n", $i, NR)
    if (NF > 0)
        lastword = $NF
}' $*
