From an existing 1:1 shift, when clicking on the blue More Actions button you will see the option to Copy the shift.
Clicking the copy link copies all of the shift settings into the browser's memory.
You can then create a new shift - the recommendation is to click in the Scheduler on the date and worker you'd like to assign the shift to. When you have copied a shift Paste will show inline with the Save button.
This then copies the information from the original shift aside from the recurring information. Any changes necessary can be made by editing the shift.