Does a low GPA (3.0) for the first Master really matter if applying for a second one?

[Manifesto95]

Hey! Really need a piece of advise. I’m a foreign student in France, studying for Masters in communication in one of the Institutes of Political Studies (IEP de région). I graduated from an APSIA (professional schools of International affairs association) member university in my country, a prestigious one, where I majored in both International Affairs and journalism. However, I didn’t apply for Sc Po PSIA Masters just after my graduation and I had to go to a regional IEP for some reasons, but I would like to do it now. I’m thinking about an international career (consulting, international organisations etc), and I realise that a regional Sciences Po (that is actually not a real Sc Po) isn’t enough for it, and I feel really disappointed. I’m going to apply for a competitive Masters in IR such as Sc Po PSIA or the Graduate Institute in Geneva, but really have a lot of doubts concerning my chances for admission. In my home university I had wonderful undergraduate marks (GPA 4.0 for 4 years of studies), but I have rather poor grades for one year of graduate studies in the regional IEP (GPA about 3.0). French system and methodology are very particular, and it has been difficult for me to get used to it (and I’m also the only one foreign student in the class, there have been no courses related to sth « international »). I’ve attended a Summer school in Sc Po to increase my chances, and I’ll also have a six months internship at the UN special agency, but I’m still not sure that it will help me to compensate the last year of studies GPA. Do you think that this low GPA for one year of Masters really matters? All the IR courses were taken during my Bachelor, and I have excellent marks for them. Hope that it's more important than communication studies.