I have a Haden mango that is perhaps around 3 years old? We moved to our house about a year and a half ago and it was maybe 6' tall and has doubled since then. I know it's a Haden because I found the tag on the ground shortly after moving in.

I was looking at it the other day so I can plan out pruning but I'm not sure if it's grafted or not. I can't find any good photos of a Haden that size to help me out. It grows up to about 6' and then there is a flat spot in the middle of the main trunk where it stop and  then the branches grow out from that. Can someone help me figure this out? I can post pics if needed.
Thanks