Usually these are two versions of an identical course - just that the M version s longer - and therefore you are actually applying for the same course twice. The clue will be if the entry requirements are identical - and this usually means that all applications to that 'subject' are considered together without quotas/target numbers for each different pathway, and that means you have exactly the same chance of any offer whichever you apply for.
Always check this with the University, just email them and check. If you are very keen on that Uni, see if you could apply for a 'similar course/subject' as well, instead of two applications for the same subject. This could also be a potential for Firm/Insurance at the same Uni if they have different entry requirements.