I've gotten cels like these multiple times.  Most
of those times it wasn't noted by the seller. 
While it's not the prettiest thing in the world,
the mess of tape and acetate, it has been at least
off the image, and I believe studio done.  Like
someone else mentioned, it's unlikely that part
would have ripped off afterwards as damage.

I'm not sure I really consider it damage, just
part of the process.  It seems unlikely to
'worsen' (like a tear, rip, crease... though I
worry about taking care of them all the same) and
it doesn't affect the image (like excessive dirt,
fading, sun damage), especially if you use a mat
in your cel book or frame.  A few of mine look
like they were done that way because the cel size
required for the paint was just about the size of
the cel, such that the cel had to be a little bit
bigger for the registration holes and the area to
attach them with tape.  I've also seen them done
perhaps to realign multilayered cels.  Many
mistakes happen in animation, that's why we often
see paint on top, correction layers, douga that
look like someone didn't study for a test and so
forth :)

Keys