I moved into this house about 10 years ago, I noticed on the furnace that one of the breakers for the electric coils is off with a note saying "Leave breaker off". After cleaning out the blower for the first time, and the electric coils of course my curiosity got the best of me and I turned it on. After the smell of burnt dust from the sitting coil its running fine. It's been completely off for years.. can't believe I never noticed it. Why would somebody keep half of the furnace off?
If it's been working fine with it off, I'd leave it off. That way you always have a backup. 2 60 amp double pole breakers, that's a lot of juice. The incoming wire may be two small. Or if your house is a 100 amp service it could trip your main breaker.
How cheap is electricity where you live? I'd freeze before I ran that thing here in Toronto.