Do I need to distribute my SPDs if I have already done so

No, it is not required for you to reprocess them. However, you may wish to complete the flow in order to store a digital copy in your documents section.

If you choose to distribute SPD's  through Zenefits, you will be prompt to download or distribute your completed SPD once the flow is finished. An email won't be sent to employees, however, they will see a pending item in the notifications center (displayed as red dot on the bell on the top-right corner of their dashboard) stating that their SPD is available in the Documents section of their account.