Hi and welcome to the Chiari forum.
May I ask what symptoms you had that the MRI was done and it appears one was also done in 2012 since it sounds like one from them was compare to this one,,,,,,,
The only thing I will say for sure is get copies of both MRI's and get a 2nd opinion......
Many Drs and radiologists are not aware of what constitutes Chiari...and they may refer it to mild cerebral tonsillar ectopia.....Drs that study and focus their practice on Chiari and related conditions.