When someone wrote to me asking why I had their 
cel in my gallery, I went over their cel scan 
with a fine tooth comb and pointed out all the 
differences in the two. Literally it worked out 
to a hair moved here, a line was different there, 
etc. . . Then I mentioned that cels close in 
sequence will have only very tiny differences 
between them. (I made sure to say it in a way 
that conveyed the notion of: "Of course you 
already know this, but. . .") That was sufficient 
to prove I had a different cel.

Finishing up with a smilie and a "I love to find 
cel siblings!" seemed to put them in a much 
better mood than when they first wrote to me. ^_^

Interestingly, like with you, it was one of the
"lower-end" cels in my collection. . . Something 
no one I can think of would pretend to own. ^_^;;

Many Sharp Smiles,
--Drac