1- Where are you doing your undergrad?
2- Where are you applying for postgrad?
The more quantitative modules you do at undergrad, the better. Also the overlap between say advanced econometrics at undergrad and the core econometrics at postgrad depends entirely on the universities in question. Pretty much all universities have their MSc follow on directly from their own BSc. Hence if you go to a top uni and do advanced quantitative modules and then go to a technically weak MSc programme at a pretty weak university, you're unlikely to cover anything new.
On the other hand, the reverse is true. So if you go to a good uni for your BSc, choose very quantitative modules, and then go to an even better university for your MSc, there will be a noticeable step up and hence doing the more quantitative modules during your BSc will help to bridge the gap.
Apart from that, the MSc tends to be much more quantitative and none of the optional modules (i.e.: trade, labour, industrial, etc.) will require more than the preliminary maths/stats module and also the core micro/macro module covered during the MSc.