Virtually any pre-1920 deed or will written in a book at the courthouse is not the original. The grantee got the original deed and the courthouse made a handwritten copy. As technology developed, microfilm copies, photostatic and other kinds of copies were made. But that deed from 1850 that you found in a book with all the others, it was a handwritten copy and could contain an error or two.
Wills recorded in a will record book are the same way. Of course, the original will may be in the packet of estate papers, but anything "recorded" before photocopies and the like was a handwritten transcription. Just a little something to keep in mind the next time you make a copy of a will from 1820.