This happened during several races and was common practice at the time as can be seen with other sponsors names that took the place of Mercier for example- A. Leducq, A,Magne, F.Pelissier, Le Greves and M.Archambaud.
Examples of the different jerseys can be found on the French website memoire du cyclisme.
[5] After Bobet had left the team, Magne directed Frenchman Raymond Poulidor who challenged Jacques Anquetil in the Tour de France but also won many other races including Milan–San Remo and the 1964 Vuelta a España.
[7] During this time, Cyrille Guimard emerged as a contender for stage races, winning the Points classification in the Vuelta a España and leading the competition and sitting second overall in the 1972 Tour de France until the second last day when he was forced to retire with an injury.
Zoetemelk challenged Bernard Hinault in the Tour de France in 1978 and 1979, wearing the yellow jersey as leader of the general classification in both editions.
In 1980, Zoetemelk changed teams to the TI–Raleigh squad where he won the Tour, and then returned to Mercier in 1982.