Yes. You can bring in multiple data sources.
About blending.....it depends upon your view. If you want these two data sources to speak with each other in the view then you have to blend it based on any common field.
But if your dashboard does not require blending....i.e, if there is no relation to be set between these two data sources then there is no need of blending. You can create worksheets separately and bring it together on a dashboard.
Hope that answers your question