estimating for reusable functions

Hi,

I am attempting FP for a software application where there are 20 Functions that are similar from coding perspective – they effect different data files and have different data elements.

Is it really OK if i count them 20 times when i know while coding effort will be involved for only the first function and for the rest the code will be copy pasted with some minor modification.

How to handle such situation wihile doing FP estimation.