Hi SumGuy,
Post #8 here includes the better options and possibilities I’m aware of in the SW Ontario area.
Many of the manufacturers listed there still make two sided mattresses and a few phone calls will identify which of them are closest to you.
Just in case you haven’t read it yet … I would also make sure you’ve read the tutorial post here which can help you make the best possible choices … and avoid the worst ones. Even a two sided mattress that uses very low quality materials won’t be a durable choice even though it would last longer than the same materials and design in a one sided mattress.
There is also more in post #3 here and the posts it links to about the pros and cons of a two sided mattress.
Phoenix