Cels Forum

While cutting cels like you mentioned isn't uncommon, it's 
not something you normally see on newer cels (eg cels
made in last 30 years).  

On older cels this is not an unheard of occurence.  When
the acetate or nitrate of the cel either starts to decay,
gets damaged or severely bent it is common to restore the
cel.  In this instance what is done is the image(s) are
cut from the original cel and then pasted onto a new cel.
The restorer will take great care in the process to cut the
image as close to the trace lines as possible without 
cutting them; and then paste them onto the new acetate as
accurately as they were on the old one.  Thereby preserving
the image positioning on the cel.

This is normally done on 'dipped' cels from the 40's, or
older cels made from nitrate where the cel itself is rotting.
It's one of the few ways to save the cel from total destruction.
Without knowing more about the cel it's hard to tell the
cirucmstances around your particular occurence.

This process is not particularly cheap though, generally it
starts at $200-$300 and can go much higer depending on the
complexity of the task.  So doing this on a $30 dbz cel would
be pretty much of a waste, as compared to something like
a B&W astroboy or Jungle Taitei cel.