1. Apart from moral issue, We are allowed to do that. If not, that is just a simple check in the software by verifying your name, DOB and, document number and stopping you from create the new account. It is just a simple 5-10 lines of code.just because it's feasible doesn't mean it's okaynot to mention having literally two ITAs. Consultant should've closed the first account the moment he created a new one.
Unless they forgot their password or in my case created an account with my spouse as primary until we got my documents back and realized we were better off going on with me as primary, there's advantage to creating multiple profiles. it's just hogging places and taking the chance away from others.
https://www.canadavisa.com/canada-immigration-discussion-board/threads/two-itas-for-two-different-profiles-is-that-possible.348108/
2. In net, you don't even take chance of anybody. You are not going to accept 2 ITA anyway, which mean those extra ITA will go back to the pool and the next person will be selected. By analyze data, CIC can figure out there is high declining rate, mean they will increase the draw size, because they still need to meet to quota of people who landed as immigrants also.
P/S: quota is landed immigrants, not number of ITA given.