graphing - if same timestamp what happens

So right now I wrote a python script that parses out my apache log for time taken to respond for certain url's and then send it to carbon.

Since we have so many requests a sec, it is possible that we are getting the same url multiple times with the same exact timestamp but a different metric value.

When it is sent over to carbon with the same timestamp, what happens does it overwrite the last one? So say I have a metric sent 4 times with same exact timestamp it uses the last one?

I set it in carbon to do 1 second, but is it possible I need to do it maybe even smaller though I know it not possible.