Am I right to think that perhaps one of the reasons some people don't get shortlisted for the next stage after application is indecisiveness. I mean, is it right to apply for more than a position in same vacancy advertisement by an organization especially if he is qualified. Or is that another smart way of boosting your chances to get called up?

I don’t think it’s right to do that, you might miss out on both. However, if you apply for one and the interviewer figure out you’re better suited for another position, you might be interviewed for that.