Goodreads Librarians Group discussion

I think this has been mentioned before, but I couldn't find it using a search.

I want to add the original publication date for a book. However, it is a 2-in-1 containing the first two books in the original series.

http://www.goodreads.com/book/edit/12...

Is the original publication date
a) the date that both books became available, i.e. the same as the original pub date for the second book
OR
b) the first time the 2-in-1 edition becomes available.

a.

That's what I thought I remembered, but I couldn't find the previous discussion on it. Thanks. :)