Can't use widgets twice – side bar and front page

Hi. I have my WordPress site set up for a special front page widget area (i.e. standard WordPress option to have side bar widgets for all pages, but front page, and then a separate widget set for the front page). When I place widgets in the side bar, I can always also place them on the front page as well. Except for Spiffy Calendar widgets. I must choose between either putting them on the general side bar OR on the front page, but I can’t apparently do both. Any advice on how I can fix this?

https://www.ads-software.com/extend/plugins/spiffy-calendar/