In The Complete Scoundrel, there are two prestige classes: Magical Trickster and Uncanny Trickster. Both have three defined levels.
Magical Trickster, in addition to its own inherent goodness, provides spells and casting as +1 level of your current casting class for levels 2 and 3.
Uncanny Trickster, in addition to its own inherent goodness, provides "+1 level of existing class features," again at levels 2 and 3.
Would it therefore be valid for a character who, assuming he meets all the prerequisites of both, to take a level of Magical Trickster, then three levels of Uncanny Trickster, and functionally end up with all three levels of both stacked on top of his pre-existing spell casting class?