The french phrase means''too much of the same thing''.Here is the story.One of the French kings was reproved by his confessor for conjugal infedelity---the king had many mistresses.The king asked the priest what was his favourite meal.Now when the monarch found out that patridge was his confessor's favourite dish,he ordered that the priest be given this delicacy for breakfast,lunch and supper.After a few days the priest hated the very sight of his favourite meal and he said to the king: ''Mais oui,perdrix,toujours perdrix''.''Ah!ah! replied the amorous monarch,''and one mistress is all very well,but not perdrix,toujours perdrix''.
Taken from Brewer's Concise Dictionary of Phrase and Fable.
