settings on one blog affecting another blog

I recently copied my WordPress site from one webhost to another webhost. (Technically speaking, they are the same webhosting company, but different accounts.) For the sake of discussion, the original host is at abc.com, and the WordPress site was copied to def.com.

The WordPress site was copied by
1. Copying all the files using FTP.
2. Exporting the database from abc.com and importing it to def.com.
3. Changing the wp-config.php file at def.com, including database name, user, password, WordPress address (URL), and site address (URL).

My problem is that when I make certain changes to WordPress settings in abc.com, the changes also show up in def.com, and vice versa. If I add a user or change a user’s password in abc.com, the same change is reflected in def.com. The same thing happens with the Site Title (Dashboard > Settings > Site Title). This is not good! I need both copies up and running separately, since def.com is a live public-facing site, and abc.com is for development and testing. I do not want the programmers with access to abc.com to have access to def.com.

Let me know if you need any other information to troubleshoot. Thanks in advance.