Yes, the total reflectged energy of a material can be greater than the incoming energy. That's true forall three renders: scanline, OpenGL and the ART Ray Tracer.
I have made a subtile change in the way the environment reflection materials work for the latter two so that they aren't additive but this hasn't been reflected in the scanline renderer yet - so 100% environment textures are added to the materials color. I will be changing it to a lrp soon. This change is a move in the direction of energy conservation.
Note that without true radiance calculations in the shader it can be difficult to get the look that you want when energy is conserved. Hilights can easily be tooy dim.
