Currently, the application will reuse an existing popup to avoid accumulating a large number of open popups with a variety of information. I know it can be a little frustrating when trying to multi-task in the application, but having previously worked with an application that did allow multiple popups, it is preferable to minimize the number of open browser windows. I once saw a user with so many open browser windows, each in an Edit mode, that the machine crashed (the user lost all of their unsaved data, probably 40-50 records).
Either way, this doesn't address what you are trying to accomplish in Daptiv - there may be alternative ways to help you get what you're after. In this instance, are you just looking to compare schedules or modify them in tandem? Or, are you trying to adjust one schedule based on the current state of another?