I am deeply involved with the placement process at IIT K and I would like to shed some light on the placements here that I have seen myself.
Placements depend on a lot of factors. One of the most important ones being a good job market, with firms willing to hire graduates right out of college. Secondly, it depends on how good the students of a particular institute are, which is never a problem for at least the top few IITs.
Now comes the question of M.Tech v/s B.Tech v/s Dual Degree, and whether M.Techs are hired by companies or not. Usually, masters students come to IITs by clearing GATE, which is not considered as tough as JEE (and I partially agree with this). This answer can be split into two parts :
1) Non-core profiles : Companies which come for analyst profiles, like financial firms, stock trading firms, investment banks, etc have the notion that if a student has not cleared the JEE, he/she is just not good enough for their profile. That is believe is false. If you look at the recent past, companies have slowly, but surely started opening for M.Tech students for recruitment as well. Although the level of recruitment for Mtechs in this area is still really low.
2) Core profiles : Companies which are considered to be core for some departments, like Tata Steel, Tata Motors, Shapoorji Pallonji, Microsoft, Google etc are recruiting specifically for core roles. These companies mostly open for M.Techs easily, and if found good enough, recruit them as well. In fact, in a lot of cases, M.Techs are preferred over others for recruitment. That is because of the following reasons :
a) M.Techs have already spent two years more than B.Techs in the core area of that branch. Hence they are supposed to have deeper knowledge of the area, which in many cases is true.
b) M.Techs are already done with their masters education and the chance that they will further go for a PhD is really low, compared to the chance that a B.Tech student will go for his/her masters, and in turn not join the company.
c) M.Tech students are usually from the top ranks of smaller and lesser known regional colleges, compared to JEE cleared people who are usually the top ranks from 10+2 level.
d) M.Techs have usually lesser load in the curriculum than their B.Tech counterparts, due to which they get more time to be better prepared for placements, and eventually perform better in the tests/interviews.
Regarding the anonymous answer “Bhai CS ka ho toh kuch bhi chalta hai nai toh non CS ka UG-PG dono ka kuch nahi hota” (Translation : If you are in CS i.e. Computer Science, then anything works. Otherwise for a person from non-CS stream, nothing works for undergrad or postgrad), there is not much that can be done in this case. It is true, that CSE students get placed really quickly and also get really good offers from their core companies than other branch students. I believe that is so because computers are still not at a saturation level in the world, where the hype over them would die down over time. Companies are still coming up with newer and better products, and hence there is an almost constant demand in the market for programmers.
However, that does not mean that a person from CSE has to just turn up on the placement day and he gets a job for free. It is not easy at all for the CSE students to get placed as well.