When an AI has stacked several armies on top of one another, and moves all of them to destroy one of your resources (in my case a scenic view) you get one warning message about it for each of the armies. For example, the first time this happened, Magnar hit my scenic view with a stack of three armies, and I got three warning messages. The second time, while I was rebuilding it, he hit it again with five armies, and I got five warning messages about it. One would suffice, especially to remove confusion about whether more than one resource was destroyed.
