Has it ever happened that a cyclist has won all three of the main jerseys (yellow, green and polka dot) in the same Tour de France?
The 1969 race is unique in that it is the only time that a single cyclist has won not only the general classification, but the points classification and mountains classification as well.
Merckx also won all three individual time trials (excluding the prologue), three other stages, the "combativity" classification, and somewhat unsurprisingly by this point, the combination" classification. His team, FAEMA, won both the team competition and the team time trial. Eric Leman did win the intermediate sprints classification so it wasn't a complete clean sweep.
In 1969, Eddy Merckx won the general classification, the points classification and the mountains classification, a unique performance in the Tour de France.
On four occasions, the winner of the points classification was also the winner of the general classification: three times by Eddy Merckx, and once by Bernard Hinault.
The general classification and the mountain classification were won by the same rider ten times, by seven different cyclists: 1938: Gino Bartali, 1939: Sylvère Maes, 1948: Gino Bartali, 1949: Fausto Coppi, 1952: Fausto Coppi, 1959: Federico Bahamontes, 1969: Eddy Merckx, 1970: Eddy Merckx, 2008: Carlos Sastre, 2015: Chris Froome.