I agree with Kenneth and Northerncat. Two 60's won't give the same performance as a 115. I've had 2 x 60's on my previous boat which is the same boat I now have with one 115. The 115 with a high pitch prop performs about the same as the two 60's on bringing the boat on the plain, after that the 60's are left behing very quickly.
If the 115's prop pitch is to be dropped to a 17 or an even more radical 15 pitch for high torque, the 60's won't even come close.
The idea to use two motors instead of one is only for safety - if your one motor fails you can still get home and not drift off with the current and when you hear 'clonk !' you say is this the Nort Pole or South Pole.
This could be significant since Father Christmas is at the North Pole (I saw this movie once...). Besides .AU and .NZ I doubt there's very little else at the South Pole