Repeated Submissions means that your audio file(s) on the album already exist on another album with a different artist name in Apple/iTunes but they have different album titles or different track titles.
Metadata for any specific audio file must remain consistent into perpetuity.
Some stores, like Apple/iTunes, will remove duplicate copies of the same audio that is submitted with different titles or artist names. They specifically call this "Repeated Submissions". If this happens, there is absolutely nothing that Catapult can do about it, since it is their store and it is their rules.
For example: If you submit a Single track album where the Artist is "Johnny Rockstar" and the Track Title is "Somewhere Over the Rainbow", and then later submit another Single track album (that is using the same audio file as the first submission)...but this time you set the Artist as "Sally Rockstar" or the Track Title as "Dancing on the Ceiling"....this is a Repeated Submission and the stores may remove it (And again, there is nothing that Catapult can do about it).
Please note, this SAME rule applies if another artist has submitted the same audio file on their album and provided different artist names or titles (This is often the case when 2 different artists worked on the same project and then submit the audio file on their own unique albums but the artist names or titles are different).
*You can submit the same audio file on more than one album so long as the Artist information and Titles are the exact same (ie: This is very often the case when a user submits a single...and then submits the full album later that includes that single). But that situation is not what this article is referencing.