Hello Sharanesh

Both of the options are pretty good, it depends on your field of interest that you opt for any one of them. Considering the case that you are comparing B.Tech course in mechanical and dual degree in microelectronics, then could see other factors. Dual degree comprises of a 5 year course, thus you save  1 year than if you take first B.Tech then M.Tech( it will be of 6 years). Although, if you are planning to go for research( MS ) or MBA after engineering, then you should rather go for 4 year course, because it will save your 1 year. Coming to the placement statistics, companies do recruit people from both the branches. It depends on how efficient you are. You may also be placed in a non core sector even if you take mechanical. And electrical is, well, pretty good to fetch a package.
Also, consider the fact that a 5 year course can be a little hectic, because the first year of M.Tech and last year of B.Tech have to completed in a single year. So make sure that you can handle that pressure and ready to put that extra efforts.

If the choice is between dual degree in mechanical and dual degree in microelectronics, then you should go for electrical as it is an emerging branch, mechanical is going pretty off these days. Although, if you are deeply interested in core mechanical field and can prove yourself there, you can go for it. I made pretty clear above that how it goes for the dual degree courses.

I hope this helps. Feel free to ask any other queries.
All the best!!!

Hey. First of all it totally depends upon your internet. Secondly according to me microelectronics is an emerging branch hence will have more opportunities. Though Mechanical is also good.