You might be able to fool a few people for a while.
You might be able to use multiple accounts to get the community off the ground. You can use dummy accounts to initiate the activity you want other members to imitate. You can use the law of social influence to get members doing what you want.
But it doesn't take a genius to figure out that there is a stupid idea.
First, it's difficult to sustain. It distorts the community reality. It distracts you from the important work you should be doing. It causes you problems in the long run. In a normal community effort, if things aren't taking off you need to narrow or change the focus. If you're distoring things, you might never know you have a problem.
Second, it's the riskiest thing you can possibly do. If you get caught, it's game over. It's really hard to have multiple accounts and not get caught.
Do they post at the same time? Do they use similar language? Do they never argue with each other? Are the contributions a little too similar? Is there a lack of personality amongst them?
Put simply, don't do this.