Hi Mark,
Thanks for returning to the Disney Parks Moms Panel with your question.
Unfortunately, Disney Vacation Club members do not get a discount on rentals including strollers. This exclusion is listed in Portable Perks, available for download at the
Disney Vacation Club Member website, under "Member Extras" and then "Perks and Discounts." Portable Perks is a great resource for determining discounts available to Disney Vacation Club members.
The best way to find lots of photos of the double strollers offered for rental at Walt Disney World is to use Google Images. Go to images.google.com and search for "double stroller Disney World." Look at the pictures of the hard molded plastic strollers, as these are the ones that Walt Disney World rents - they are tan or purple in most of the images on this page. By using Google Images, you'll see lots of pictures, including empty strollers and ones with children in them. If you look at some of the ones with children, you can estimate how big your children are in reference and make a judgement as to if you think they'll be comfortable.
According to the official Walt Disney World website on strollers, a double stroller is recommended for up to 100 pounds, so adding your children's weights together will let you know if they fit in this guideline.
I hope that this information helps, Mark! Your trip is so soon, you must be getting really excited! Please do come back and ask if you have any last minute questions. Have a wonderful trip!