the values in value lists are always unique, so you have to add another attribute to your key like a serial number.
First Name and Last Name can be combined in a text field with an auto-enter calculation to use with this value list as the second field with an ID field as the first field. A unique values validation on this new text field can prevent records with identical first and last names.
It is also possible to set up an auto-complete enabled value list of names with a look up and scripted support. The script can detect new names and names with duplicate matches and take appropriate action such as offering to create a new record for new names and presenting the user with a list of matching records from which to select when there is more than one matching name. The list can include additional fields such as an address and/or phone number to help the user determine which individual to select.
Thanks a lot for your reply PhilModJunk.