Here is a simple fix that is easy and will hold. From your picture I recommend doing this for the down-tube water bottle cage. Get a 3/4 inch by 1/8 inch aluminum bar (most hardware stores will have them), a 5mm .8 thread tap and tapping tool and two more water bottle mounting screws. Cut the bar to size so that it will work when you do the following: Drill two 13/64" holes in the bar spaced so they will line up with the bottle cage mounts on the frame. Then drill two 5/32" holes far enough from the 13/64" holes so that when the cage is mounted in these holes there is enough room for the other cage. Then tap the 5/32" holes and you are ready to mount the cage. First mount the bar and then mount the cage to the bar and be sure to use thread lock. Sorry I don't have a picture but I did this on a friend's bike and it worked very well.