Yeah tcmeric had basically covered it.
If youre not fammiliar with arrays or do not want to use them, you could just create 3 int variable and just check that the second one you make is not the same as the last one (or last 2). This will be the clumsy long winded way of doing it though haha.
So:
3 variables: int1, int2, int3
First state: Set int1 to random int. Move on.
Second state: set int2 to random int, check if same as int1 or different. If same, Move on to state 3 if different move on to state 4.
state 3: set int2 to random int., check if same as int1 or different. If same, Move back to state 2 if different move on to state 4.
State 4: set int3 to a random int, check if int3 is same as int1. If same, Move on to state 5 if different move on to state 6.
State 5: set int3 to random int., check if same as int1 or different. If same, Move back to state 4 if different move on to state 6.
State 6 check if int3 is same as int2. if same move back to state 4, if different move on to state 7.
State 7: do whatever you want to do with your 3 ints.
This is of the top of my head but shoud work i believe. Although tcmeric had a much cleaner solution, I thought I would still pitch in with the clumsy noob way of doing it.
Good luck with it!