python precission

Hi All:

I have just started programming some scripts in Arcgis. So, the problem i have encountered is the next one.
I traverse all the vertices in a shp feature, and create another shp with all the vertex discarding the overlapping ones.
But... when the script is finished, they are not in the exact point they should be.
I wonder if its a python precission problem, or a round problem i dont know how to stop.

In the other hand, i have noticed that when u apply a topology to a geodatabase, there is a parameter 'tolerance' that make my geometry be modified. Maybe there is something similar in this process im developing.

Any advice appreciated!!

Thanks!!