Began as F1 student in 2012, now in 6th year. School says I am a Resident Alien for 2017 tax purposes but ALSO a Dual Status Taxpayer. Am I dual status or RA??

I have always been on F1 visa. I started studying in 08/2012 and in 2017 became a Resident Alien for tax purposes in July (I assume through Substantial Presence). But my school is telling me that I am also a Dual Status Taxpayer as this is the year I became RA.  I thought that the year you turn RA counts for the entire calendar year, and that 6th year students file regular 1040, not dual status.