Provide a way in the URL to display information two or more places at once

[mrjohnc]

Enhancement request

It would be really great if I could produce a map that showed monuments from two or more areas in one map. I guess the easiest way to do this would be to allow users to add two Q numbers to the URL in some way (in bold)

https://tools.wmflabs.org/monumental/#/list/**156990**?c=51.8100:-2.7200:7&heritage=1