Cannot avoid override property for each element inside a loop?

I have an issue. There is an object with a list of elements...

I have a for looping on the list and then I do this

for(Object myObject:myObjects){
   myObject.setProperty(someService.getMyPropertyById(id));
}

Seems like it overrides all the elements by a last element property.

I also tried creating a fresh list before the for and then add myNewList.add(myObject) with the hope to avoid this but same result.

Any idea how to archieve this? Sounds quite easy but im struggling a little bit.