title: Why do 3D models have duplicate vertex positions with different uv coords
body: <p>I am experimenting with exporting the Collada format from Blender, and with using more complex objects and texturing, I have noticed during the index "p" section, it will list the same vertex information but using different normals and uv coords.</p>
  
  <p><strong>Two main questions that I feel are pretty important.</strong></p>
  
  <p>1:  Why?  Shouldnt it only have 1 vertex position and 1 UV coord for that position?</p>
  
  <p>2(the most important question of all): What happens if this vertex information gets put into the Vertex Shader out of order?  For example, Index 1 vertex, and index 10 vertex share the same Position, but have different Normals and UV Coords. What if Index 10 went first, and then Index 1?  And vice versa, does this change anything inside of the Pixel Shader?  How does this effect the rest of the pipeline?</p>
  
  <p>Thank you!</p>