Combine two certified datasets

HI Anonymous 

As far as I know there's not a way of combining Datasets, certified or otherwise, to create a new third Dataset that contains data from both. You'll have to build a new Dataset bringing in the data from the original locations and combining them.

However you can access two Datasets at a time as one "Composite Dataset". This is still a preview option in Power BI, I've written about it in detail here..

Power BI Composite Models | What’s The Big Deal? | Burningsuit

Hope this helps

Stuart