Quoted from PinMonk:Yep. Some people have done that configuration. Most R&M that are going out are the 3 flipper kits, but I have both 2 and 3 for this exact reason, and I will have a one bracket add-on soon for people that bought before the 3 flipper was available or got only 2 but later decide they want all three to be the same performance level.
The left doesn't seem to get as hot on R&M. But if both the right are cooled for a very long game the left might get hot enough to start to fade. In that case it might feel "weird" to have the right side shooting great and the left fading, but given that the left stays cooler longer, I don't think it would be an issue for most players.
Just purchased the three flipper kit from Pinball Life along with some other parts I needed!! Thank you Vireland!