Hi,
Yes, it's possible to download more than 1 study:
"By default, the study will be downloaded to the active viewer window (if another study was previously opened in this window, it will be closed). Other download modes are available from the pop-up menu displayed after clicking the right mouse button on the selected study/studies. Click Add to active window or press Shift + Enter to download the study to the active window without clearing previous study. Click Download to new window or press Ctrl + Enter to open a new window and start downloading the study to it. Click Download to separate windows or use the shortcut Ctrl + Shift + Enter to download each of the selected studies to a new window."
http://www.radiantviewer.com/dicom-viewer-manual/opening-a-study-from-a-pacs-se.htm
Greetings,
Maciej