I checked those Finnish book sources that I mentioned more closely, and Suuri jääkiekkoteos 1 (1979) and Leijonapolku Jääkiekon maailma (2014) have Holecek-Pospisil-Martinec as the Diretorate award winners, whereas Huippu-urheilun maailma 2 (also from 1979) has (Holecek-)Waltin-Kharlamov.
Looking at those other sources provided in this thread, every one of them also seems to follow the similar pattern, i.e. if they list Kharlamov as the winner of the Best Forward award, they also list Waltin as the Best Defenseman (and when Martinec is BF, Pospisil is BD), it's never Waltin-Martinec or Pospisil-Kharlamov, right?
So, clearly there are two different kind of original sources, the 'right' one and the 'wrong' one, and those later sources have followed one or the other.
A fine observation!
How unlikely is it that the IIHF Directorate would hand all three awards to the same team (Holeček, Pospíšil, Martinec)? It has never happened before or afterwards:
1954: a Canadian, a Swede, a Soviet
1955: an American, a Czechoslovak, a Canadian
1956: an American, a Soviet, a Canadian
1957: a Czechoslovak, a Soviet, a Swede
1958: a Czechoslovak, a Soviet, a Canadian
1959: a Soviet, a Canadian, an American
1960: an American, a Soviet, a Swede
1961: a Canadian, a Soviet, a Czechoslovak
1962: two Swedes, an American
1963: a Canadian, a Swede, two Czechoslovaks
1964: a Canadian, a Czechoslovak, a Soviet
1965: two Czechoslovaks, a Soviet
1966: two Soviets, a Canadian
1967: two Soviets, an American
1968: a Canadian, a Czechoslovak, a Soviet
1969: two Swedes, a Czechoslovak
1970: a Fin, a Swede, a Soviet
1971: two Czechoslovaks, a Fin, a Soviet (four players honoured)
1972: a Fin, a Czechoslovak, a Soviet
1973: two Soviets, a Czechoslovak
1974: a Soviet, a Swede, a Czechoslovak
1975: a Czechoslovak, a Fin, a Soviet
1976: in question (either three Czechoslovaks or a Czechoslovak, a Swede, a Soviet)
1977: two Soviets, a Swede
1978: a Czechoslovak, a Soviet, a Canadian
1979: in question
1981: two Soviets, a Canadian
1982: two Soviets, a Czechoslovak
1983: two Soviets, a Czechoslovak
1985: two Soviets, a Czechoslovak
1986: two Soviets, a Swede
1987: a Czechoslovak, a Canadian, a Soviet
1989: a Czechoslovak, a Soviet, a Canadian
1990: two Soviets, a Canadian
1991: a Fin, a Canadian, a Soviet
1992: a Swede, a Czechoslovak, a Fin
1993: a Czech, a Russian, a Canadian
1994: two Canadians, a Swede
1995: two Fins, a Swede
1996: a Czech, a Russian, a Canadian
1997: two Swedes, a Canadian
1998: a Fin, a Czech, a Swede
1999: a Swede, a Czech, a Fin
2000: a Czech, a Fin, a Slovak
2001: a Czech, a Swede, a Fin
2002: a Russian, a Swede, a Fin
2003: two Canadians, a Swede
2004: an American, a Swede, a Canadian
2005: a Czech a Russian, a Canadian
2006: two Swedes, a Canadian
2007: two Russians, a Fin
2008: two Canadians, a Russian
2009: a Belarusian, a Canadian, a Russian
2010: a German, a Fin, a Russian
2011: a Swede, a Canadian, a Czech
2012: two Slovaks, a Russian
2013: a Swede, a Swiss, a Fin
2014: two Russians, an American
2015: two Canadians, a Fin
2016: two Fins, a Canadian
2017: two Russians, a German