Need to generate pair of numbers from a given range in C#

Well, I need to generate 2 numbers within the range of (1,8). Suppose, The first two numbers are 3 & 4. In second time the range will exclude 3 & 4, that's what i want to accomplish. In this way the loop will continue for 4 times.

I have been trying it...but cannot proceed
All I know is to use Random Class

The range is fixed

Any type of help will be accepted.Thanks in advance