Different Random numbers for different instances of a class

[Chiefy]

Im writing in C# and I currently have a class called allocation that has random numbers like,

students[0].choiceTwo = Randnum.Next(15);

obviously using the Random class. The random numbers are part of a method called Allocate.
In my main method i have created 2 instances of the class

Allocation first = new Allocation();
Allocation second = new Allocation();
first.Allocate();
second.Allocate();

However the random numbers are the same for each instance when i need them to be different. How do i go about sorting this?
Thankyou

[Chiefy]

Dont worry have sorted it myself, silly mistake!