You can share a copy of the reminder with someone else, who can then can add it to his/her own copy of Due.
Tap on the share button on the bottom and select ‘Add to Due Link.’ You’ll be given options to share a link to someone, who can then use the link to add a copy of that reminder to his/her copy of Due.
Do note that this is just sharing a copy of the reminder. Any changes made to your own copy of the reminder will not be synchronised with your recipient’s copy, and vice-versa.