Imagine 2 webpages, each for one country. each has subsidiary pages for all sorts of things, including for instance a page on electrical current in that country.
Now imagine that another country comes along but this one has two cities. esch with its own page, say, London and Oxford. The electrical current is the same so there are going to be two indentical pages with different urls. Google does not like that.
I have worked out two ways of getting round the problem but am still looking for something more elegant.
The idea is that each city will link to the same page, but needs to return to the page where it was before. One solution was to give a choice of the towns: “Return to London” and “Return to Oxford” without using target blank… The other using target blank, simply asks the visitor to close the page via the x in the tab.