It's quite possible, just depends on the amount of data available to the appraiser, and what it is that is being appraised. A track home or a condo, where there might be many very similar, nearly identical, units, with recent sales comps, will have less variation than say a $4million custom home on Mt. Soledad.
Also, appraisals are time-dependent, and are an opinion of value on the day they are performed, so an appraisal done months later might reflect differences in the market, which can be substantial in a hot market, or if better data (i.e. comps) becomes more available.
Thanks for the great question, always available if you have others.