Why are you looking to get a second degree at RMC? What is your underlying motivation?:
a. You want a career in the forces;
b. You want to get extra education (a free one to boot);
If it's a, then it really depends on what trade you chose. If you want to join as a trade that doesn't even require an engineering degree, then they are likely to say no. Why would we pay for you to get a degree when you already have one that is acceptable for your desired trade? You can be a Pilot or an NWO with a physics degree.
If it's b, then sure, you can apply for a trade that requires an engineering degree, which would make you eligible for ROTP. The engineer program at RMC is really really good,. But RMC is more than just a degree program, it's also a leadership and professional development program. Even if you get credits toward your engineering degree, you're likely going to still have to do all 4 years, you might just have a lighter schedule than the other engineering student.
That all being said, if you heart isn't into eventually having a military career, than I would ask that you not pursue ROTP. Don't take a spot away from someone who really wants to make a career out of it. I had a classmate who did all 4 years, graduated from RMC and was commissioned as an officer, then immediately released from the forces even before leaving the school, and just paid the government $80k. His family had money, he just wanted the quality of education and reputation that can come with having an RMC degree.