Здрасте!
In Panda, 1 unit in an .egg file does in fact equal 1 unit in the scene. Panda does not imply an implicit scale of 0.5 to anything. In which tool did you create the .egg file? Perhaps you could share the .egg file with us?
Keep in mind that if the box vertices range from -1 to 1 in coordinates, the actual size of the box is 2x2.