How to avoid duplicates each time the script is run

Hello, I am new to the platform. I come to ask for your help on a dynamo script that I am making.
I want to automate the placement of spheres to locate interfaces. currently the dynamo creates the spheres but I don’t know how to do so that if a sphere is already created that it is no longer created each time the script is executed.
Thanks.

I think you could find all spheres in the model, pull their position and match it to the list of positions you are feeding into script, remove duplicates before feeding it into the place element node(I assume, as i cant read your screenshot:) )

You can press the camera button in Dynamo to export a readable screenshot
image

I hope it’s better


Ok do you know how I check the list of spheres, eliminate the spheres that already exist?