NO! It is your responsibility not to do so. We only provide you with a distribution platform where you can sell your music. Whenever you log in or upload your songs, you have to guarantee that you own all the rights to them. This applies also to short (i.e. a few second) excerpts from other songs.
A lot of people think that if they create a song putting together pieces of other songs and then register it with a collecting society like the German
GEMA, they are allowed to publish and sell this song. THIS IS NOT TRUE! You always need the approval and the written permission of all copyright holders, e.g. record companies, artists, publishers, and so on.
It is also common belief that you are allowed to make use of any songs for max. four seconds (or a few beats) without asking for permission. THIS IS NOT TRUE! There isn't a "four-second-rule". Any unauthorized use of intellectual property shall be persecuted.