selecting both random and nonrandom elements in R

Suppose I have a matrix in R as follows:

ID Value
1 10
2 5
2 8
3 15
4 7
4 9
...

What I need is a random sample where every element is represented once and only once.

That means that ID 1 will be chosen, one of the two rows with ID 2, ID 3 will be chosen, one of the two rows with ID 4, etc...

There can be more than two duplicates.

I'm trying to figure out the most R-esque way to do this without subsetting and sampling the subsets?

Thanks!