I think I know why it is happening - still doing testing to confirm but I think that it is the Group Discovery discovering the members of the AMT machines group. I turned off Group discovery and after a full ad resync and an hour or so all the machine names
of active computers reverted back to their proper netbios name without the iME at the end.
Going to try and turn on group discovery once I figure out how to exclude my AMT computers group....