The quoted text is from the 'Advancing Martial Progression' heading of the Prestige Classes chapter in Tome of Battle; Book of Nine Swords. It is referring to how you recover maneuvers gained by the advancement of a martial progression granted by a martial adept prestige class.
The line directly after the one you quoted
If you have levels in two or more martial adept standard classes (for example, you are a multiclass swordsage/warblade) you must decide to which of your existing martial adept classes the new maneuvres known or maneuvres readied apply
clearly indicates that it is referring to maneuvres gained by gaining levels in prestige classes, not maneuvres gained by 'martial adept standard classes'. Ergo, by RAW, it is clear that taking standard martial adept classes works under the ToB rules for maneuvres when multiclassing, found on page 39.
This is from the FAQ on the subject:
Q: If you are a multiclass martial adept (from Tome of Battle), a swordsage/warblade for example, do you have to keep your maneuvers known and maneuvers readied separate for each class?
A: If a character has multiple martial adept base classes, the maneuvers known and readied from each class are kept separate. Knowing a maneuver for one class does not mean you can ready it for the other, or vice versa.