how do i check if i have the same object/number 2 times or more in an array ?

The contains node will help you with that…
I’m being lazy and using someone else’s example (sorry I don’t remember who’s as I saved these pics a long awhile back) so all credit to This dude who posted it…

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This example is a trace that goes out straight forward from the camera and makes an array of any PhysicsBody that it encounters…
Break hit brings us to the 2nd pic attached where s/he Checks the Array to see if it Contains that actor already…
You can also use remove or a Foreach and likely many more ways to get the same results…It’s what’s fun about the Unreal Engine…1million ways to get results…
Array nodes - Array Nodes | Unreal Engine Documentation

if you have any questions…let me know…