we definately know that the writers like to use names for more than one character - Charlotte Malkin-Charlotte Lewis; Kate's childhood friend Tom-Mr. Friendly Tom - Claire's boyfriend, Thomas; Walt's step-dad Brian-Shannon's boyfriend Brian; Richard Malkin - Richard Alpert; Charles Widmore-Charlie; Emily Locke - Emily Linus (interesting that Locke and Ben moms had the same name); plus lots of small character roles that have same names, so it could be that Libby's David (which is also Desmond's middle name) and Hurley's Dave could be one and the same, or they did it just to mess with us....

__________________