Moleculwiz

While research isn't a huge deal, I think it may benefit you more than a dual degree. Assuming your grades were good, your mathematical background is sufficient for biostatistics. I think having strong letters from people who know you personally is great. Take more coursework and keep doing well, that will help more than having a dual degree. 
It's good to start thinking about this early on, good on you.

For those curious, I did some digging into this programme. U of T's School of Public Health is very new and the Biostatistics Division is accordingly very small with only 4 tenure-track faculty. As I understand it, PhD students are often advised by professors in the Statistics Department, which has a cohort of about 5 or 6 people doing biostatistics research, and by status-only professors in the surrounding research hospitals. In terms of placements, over the last 10 years (N = 21), 30% went on to be university faculty, some at U of T, and 40% went on to research institutes and teaching hospitals. The rest are in industry and government.
This information isn't easy to get hold of, so hopefully some fellow Canadians will find it useful. 

Research isn't a huge deal for statistics except in that it helps you get good letters from people who know your ability.  Your grades in math courses are more important (though the actual addition of the extra degree won't matter that much for admissions, except in that it means you get more coursework).