Spotify, YouTube and all the digital distributors (such as tunecore, distrokid and others) have an automatic system which detects the presence of audio tracks already present in their databases or if the track itself has already been loaded previously, sometimes blocking the upload of the song being loaded.
It is therefore possible that if you buy a base track sold previously and uploaded to the platforms by someone else before you, your upload could be temporarily blocked pending a reply.
However, it is sufficient to reply with an email certifying ownership or the license to use the song being uploaded and the blocking procedure will be immediately removed.
Furthermore, our backing tracks can contain royalty free samples (sounds used in the arrangement, as you can find in almost all songs produced nowadays).
It is therefore not uncommon for automatic systems to detect sounds already present in other songs.
Here too it is sufficient to reply to the email certifying the ownership or the license to use the song to unlock the procedure.
In any case, for any question or clarification on the subject, we advise you to consult the guidelines of the aggregator you are using.