How does one select last array of blockinstance rivets created?

having already created one array of block instance rivets, which I now wish to redo, I come to select last created items, my second array of block instance rivets, and icon for selecting last created objects doesnt select them. I need to select them and group them to be able to select them and make2d. I also need to to select the not so good first array and delete and redo.
They are all from a circle with name rivet7mmhead, so using block manager to select that name selects all of them, and I dont want to select all of them.

I thought I had grouped the first array, but I end up selecting one rivet at a time.