I have come across this seller on ebay several times selling rare tome's.
I resisted buying anything from him as it looks to me like they are photocopies.
Try asking for a photo, I got no response which made me suspicious.
PeteG

They will be taken from the original volume. However, the last page is probably on the reverse of the first page of the next article. Obviously both can't have the original page, so people always use a photocopy of the last page.

Using a photocopy always means its a broken up tome and not an offprint as this bloke says.