No, it's written correctly - inc one st at each end. That means at both the beginning and end of the next row and every other row after that, 4 more times, which is 5 times altogether (next row, plus 4 more).
The 2 row moss st is called seed st in US patterns, and is k1 p1 on the first row, then on each row after that you would knit what look like purls (on that row) and purl the ones that look like knits. So inc in the first last st, or between the edge st and the one next to it, depending on which inc you use. Work the rest of the sts in the pattern (knit the purls, purl the knits), and on the next row, include the new sts in the pattern.