In Berlin and we assume other cities when statues require repair, concrete stunt doubles are erected in their place while the work is being done. This is probably in the interest of historical continuity. Nowadays tourists come pre-armed with Google-like power recognising sites from photographs and they notice when a bit is missing. This calls for a lot of statue management. We noticed one of the by-products on the border of the large park used in Documenta. In a small shed behind one of the installations you could see a small gathering of statuary out the back, taking a break between engagements.