I migrated a SPS 2003 site collection to MOSS 2007 using database migration. There are already some document libraries in the SPWebs of the site collection. Some of the libraries are just the standard columns - Created, Modified, Checked out by and Title. The libraries don't have content type management enabled since they were migrated from 2003.
Here is the strange part - when I enable content type management on any document library (of this migrated site), all the existing columns in the library are getting associated with the Document content type, when I would have expected only the Title column (which is a Document content type column) to maintain its association.
In the same website, if I create a new document library and enable content type management, only the Title column is associated with the Document content type. No other column is automatically added, as with the libraries that were part of the migrated content.
How can I prevent the behavior exhibited by the migrated content?