Yes, there's that much variation among total climb readings. Were all the uploads to that ride, from Garmin Edge GPS's? Also, MotionBased has two levels of correction. They advise not to use their correction with Garmin Edge units, because the unit data is more accurate (barometric altimeter corrected against known points). Garmin Forerunner units don't have the barometric altimeter, so MotionBased advises using correction with them. MotionBased also notes that their correction protocol will exaggerate total elevation gain on routes with a lot of steep climbs. That's true even (and I think especially) when the individual hills are not tall.