Hello,

I wonder whether this is intention, but I couldn't think of a reason why you would do so. Why is the field "name" in core_members not set as unique field ? Since this field is being used as login name it doesn't make sense to allow duplicates here or am I wrong?

While we do not allow duplicate names out of the box, it is conceivable a plugin may want to and indeed many SSO plugins out there do not prevent duplicate names. In short, we could add a unique index on the column to enforce unique user names but we simply chose not to - not for any specific reason out of the box.

It is also important to note that adding one would affect upgrades. If a site does have duplicate names (due to a plugin or due to some past bug) we would need to handle those on upgrade some way.