Yes, the pole with less of it protruding above ground is more likely to support a weight, so the one with 6'6" above ground offers more flexibility so will bend first, assuming the poles are made of the same material and are of the same thickness. Hammering a nail into wood or brick is a similar situation. At the beginning the nail is more liable to bend when very little of it has been hammered in, rather than at the end of the job when only a short length remains.