If your background is actually a Tiled Background Object, I recommend using just one tiled texture and resetting it instead of spawning one object after the other.
[Tiled Background] Y is less or equal to Self.Height
[Tiled Background] Set Y to Self.Y - Self.Height / 2
Just set the height of your object match your LayoutHeight * 2
(I am assuming you are scrolling vertically. Otherwise, set Y and Height to X and Width).
For reference, check the Auto Runner Template that comes with Construct 2, there is a horizontally auto scrolling background in there.
Let me know if this help