One of the sites (My guess is hockeydraftcentral) made a mistake on when round 9 ended. Whether Mike Lampman was the last pick of the 9th round or the first pick of the tenth round. This pushes back/up the rounds the final players were drafted in. Both sites have all the same players.
Both have the same players, and it's clear that the only team interested in drafting at the end was St. Louis. My preference would be to count a new round each time they (alone) picked, but it's possible that the league never enumerated exactly how the draft rounds count (since the entry draft was still new, and since it ultimately doesn't affect anything).
I'm also sure that someone has a more contemporary source (even I might, but it would be at home).
Irregularities: The NHL prohibited the Buffalo and Vancouver franchises from trading first picks and insisted that after signing the players, these teams could not trade them for at least three years. There was no set number of rounds. Teams had the right to pass in any round, and the draft continued until all teams were done selecting.
Note that with 116 players taken, the draft would not even extend to four rounds by 2013 standards. On the other hand the various NHL teams with the exception of expansion teams had players stashed away in the NCAA and elsewhere from the sponsorship era.