Issue 1

1) Currently (01-Sept-2009) when "duplicate titles allowed" is activated in the Entry Configuration settings - 
If a new entry title is made which has the same entry title as one already in the directory, all required fields (those indicated with a *) in the new entry will be cleared on the new entry when the save button is pressed.  They will all have to be manually re-entered. This may be resolved in time by the creator of the directory

Issue 2

2) If the same Title is created for two entries and any SEF Tools are being used, two URL will be generated which will be identicle. 
For example:

Entry1- Frank Spencer
This Frank is an Accountant
The URL generated by SEF = www.mydomain.com/directory/frank-spencer.html which points the the information on Entry 1 according to the SEF tools used

Entry 2 - Frank Spencer
This Frank is a News Reader
The URL generated by SEF = www.mydomain.com/directory/frank-spencer.html which unfortunately is already generated and points to Entry 1.

Consequently, the link to only Entry 1 will be seen on the live site.

Possible solution to Issue 2 is to change the Title to include more information about the users name (maybe a middle initial) or include the profession in the title.