Hi matdif,
The tutorial post includes a list of the members here that sell online and many of them make latex mattresses in a wide range of designs, price ranges, and options but My Green Mattress is the only one I know of off the top of my head that makes a range of two sided latex mattress (with identical sleep surfaces on both sides) that I’m aware of.
Posts #2 and #4 here include the better options and possibilities I’m aware of in the Chicago area but if I lived in the area My Green Mattress / Quality Sleep are the first and possibly the last retailer or manufacturer I would need to visit. As you probably know from reading here they are a member of this site which means that I believe they compete well with the best in the industry.
Phoenix