I was looking at the records in my ##__user_profile table recently and noticed there were records there for the dob field, even though that field has always been disabled on my system.

Steps to reproduce the issue

• Set up the user profile plugin and disable all fields except Terms Of Service.
• Now create a few user accounts.

Expected result

The new accounts should only have a single record in the user_profile table, being "profile.tos", with a value of "1".

Actual result

The new accounts actually have two records in user_profile table, "profile.tos" as expected, and also "profile.dob", with a blank value. This dob record should not be getting created.

System information (as much as possible)

This is on a Joomla system that is currently on v3.6.5, having been upgraded regularly since v3.4.8 as new versions were released.

Additional comments

The spurious dob record doesn't have any negative effect, other than wasting space in the database, so this isn't a particularly serious bug, but I do consider it a bug nevertheless.