All of your inputs are named the same thing? How would you expect to read them if they are all named the same...how could you differientiate between them? Now...if you named them as arrays, then you could.
<input type=text name=first_name[]>
Then, if you have a bunch all exactly like that, you can refer to them as
$first_name[0]
$first_name[1]
...
$first_name[x]
up to however many you got...
---John Holmes...