You can work with as many Angels as you need (relative to availability). You can request the same project multiple times to receive different versions of a piece of work, or work with a team of angels on a single project (when available). However you want to tackle your challenges, it's ultimately down to you and the Angel/Angels you are working with!
If you would like to work with multiple different angels on the same project, we would suggest requesting the project 2+ times. As an example, if you wanted to receive a website review from 3 different sources, we would suggest requesting the project 3 times. The same principle applies to other project types, so you can request as many as you need.