I've just submitted my first profile with extensive credits, and in selecting names from the left hand "Crew Member" column to the right hand "Name / Role", it dawned on me:

How do you know the existing crew database person is the same person in the credits you're entering?

If they're not unique, it would associate that existing person with projects they never worked on.

I know this must have been discussed many times before, but crew members don't have the same sort of trademark name as do movie stars, though the problem occurs there as well.

If all I have is a name in the credits, with no birth year, no picture, etc., it leaves me a bit confused ...

The problem to identify unknown persons is the main reason why I do not enter, in my local, crew other than main ones (as director , composer...). Lists of sound or art crew with people that we are quite unable to link or recognize are not very interesting, in my opinion. When in specific cases I want to know more, I just watch the concerned credits...