Modifying a duped record modifies the definition of that record

[moonmaster9000]

steps to reproduce:

require 'dupe'
Dupe.define :book do |book|
  book.authors []
end
b = Dupe.create :book
a = Dupe.create :author
b.authors << a

# at this point, b.authors includes a
# however, if you create a new book, it will also have that author in it
Dupe.create :book