I using Random Intger in range node.
To remove duplicates, Is that the only way to saving the already created generated number in variable?
or is there something node and function about this problem?
Save last used random and compare against next run.
Not sure if i understand what you want to do exactly, but you can always reverse whole thing and remove drawn integers from array, or have array of booleans and flip them to false.
For what you asking you need integer array to remember if numbers were used or not. There is no way around array keeping some info.
However (maybe) what you need is pseudorandom numbers that you can repeat next time (or any time) same numbers.
For that use random streams, seed (with same seed, you always get same numbers):
(Random Streams | Unreal Engine Documentation)