The question whether it's okay or not to mix various brands of paint, or whether you have to stick with one brand only, be it watercolor, acrylics, or oils, is one that comes up regularly. A variation on this question is whether it's okay to mix student and artist's quality paints. The simple answer to both questions is "yes", you're unlikely to run into any problems.
If you find the paint is curdling or lumping, then take it as a sign that there's something about the way it was formulated that makes it incompatible. This is most likely to happen only with water-soluble oil paints as these are the most "complex" when it comes to paint formulations.
