If an user renders an image already rendered with the same parameters (resize...), we should give him the previously rendered image instead of a new one, saving map IDs.

Also, reusing maps IDs from deleted posters could be an idea to save these precious IDs.

is this already support ?

This is currently useless, we have plenty enough free mapids. But we can tweak this idea to give a common map set (bank) available to a bunch of player (only get for exemple). That can lead to a shop system or a community sharing art. @AmauryCarrade