incompatible metrics

[bkph@ai.mit.edu (Berthold K.P. Horn)]

Hi:

I am looking for a documented example where two vendors supply fonts with
the same name but different metrics.

Generally I have found that some character may be different in fonts from
different vendors, but that the character escapements are the same.  
Are there exceptions?

(Actually, frequently even the shapes tend to be very similar for popular
fonts - except for non-alphanumeric characters and special flourishes that
foundries add to a single character to make their version identifiably
different from others).