A scholarship dilemma Hello everyone and thank you for your attention!

I have been just offered two different scholarships which are pretty much the same. However, the first one requires me to apply to the university and will be granted only if I am accepted. The second combines an acceptance offer + the scholarship itself (Erasmus +). 

I can't be 100% sure that I will meet the requirements of the first scholarship but it appeals to me. Only if I get rejected here (I will know that in several months), I will choose the Erasmus +.

I have just a week to accept Erasmus + and want to have this option if anything goes wrong. Can I now accept their offer and decline it later? How will that affect my academic future or whatever?

Any suggestions on how to deal with that?
You'll want to check the details of the scholarship, probably searching for terms like "deferral", "cancellation", "forfeit", etc. Most large scholarships will have handbooks, FAQs, and maybe even someone you can email directly to ask a question.

Some scholarships/fellowships can be combined, so you can accept more than one, and some can't. This is generally an unusual enough case that you'll need to ask the program administrators for the answer. In the programs I've seen, you are free to cancel or withdraw at any time with the only limitation perhaps being that you may not be able to reapply for that specific program again. 

Given that you won't know for a few months, the only thing that might not be a good idea is to reject the scholarship which is offered now, on the hope that you get the other one. Admissions, and especially scholarship money, are never guaranteed until you have been formally offered them.

Based on the limited information here, if I were in your shoes I think I'd take the guaranteed offer now, and then don't worry about it. If you get offered the other scholarship, then inquire at that time with your program and the previously accepted scholarship what your options are. Then, with the new information in hand, choose what is best then, now that you have the offers.