Do you need to view data from another stage on your Project? Within your Project use the [View Stage] feature on the Stages Modal.
Within the required Project click on the Stage Name to open the Stages Modal
Click [View Stage] on any stage which isn't the 'Current Project Stage'
You will be taken to a Read-Only window where you can view the Project with the selected Stage's data
Should you need to edit the project in this stage, you would need to set it as the current project stage.