Is this seriously the way you mark a mesh as using team-texture ?!?
If so, then the blender export script is defective.
You should set a mesh as two-sided if (and-only-if) you intend for back facing facets to be seen (ie, have translucent/transparent mesh or texture, or 'holes' in the mesh).
There'll be a new model viewer/hacker tool available "very soon" (tm) that will let you change mesh properties (two-sided and team texture are separate properties) as well as mesh opacity and diffuse colour, and add/change textures for all five slots.
If the blender export script is using 'two-sided' to set both the two-sided and team-texture mesh props, it might get much more use than I expected.