Cue,
mfgrs have been known to be "creative" when it comes to publishing their curves.
The other factor -- mic to preamp interaction -- can make a huge difference.
I have a list of stories about different mics and how they react to different preamps. I ran into this when I started reviewing mics for trade magazines. The AKG C414 (of which there are no less than five different versions which also makes comparison difficult) is very load sensitive. It can sound pretty nasty when plugged into the "wrong" preamp and quite delightful when plugged into the "right" preamp.
Some mics are more susceptible to this than others.
Regards,
Ty Ford