How to create multiple mongoDB databases and share them on heroku?
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I've popped into console and ran the "heroku addons:add mongohq:free" which added an environment variable: ENV['MONGOHQ_URL']. It is a url that looks like this:

> mongodb://heroku:xxxxxxxxxxxxxxxxxxxxxxxxx@staff.mongohq.com:10059/appxxxxxx

I want to be able to use (and share) TWO mongodb instances. Running addons:add mongohq:free on the same app fails saying that the addon is already present. 

Do I have to create a separate, blank app and just use the ENV variable from it?

Finally, is it possible to share these urls between apps? 