In this context, it would be futile to attempt to communicate any subtle or technical differences by using one of repeated or repeating rather than the other. That is, both have senses that might or might not apply, such as “Having been said or done again” and “Sequential” for repeated and “That repeats; repetitive” and “Of a decimal: recurring” for repeating. Regardless of which term you use, the reader is likely to conclude that some structure occurs several times in the data. If that is what you mean to say, I recommend using the term repeated because it merely communicates the fact that a structure occurred several times instead of allowing the interpretation that some structure that can repeat occurred, once or more.
For better specificity and precision, consider using different wordings (depending on the facts), such as:
• Some structures appear in the dataset more than once.
• Some structures appear in the dataset multiple times.
• All structures appear in the dataset more than once each.
• Every kind of structure appears in the dataset at least twice.
• Each structure recurs in the dataset infinitely often.
• No structure in the dataset is a singleton.
• Some structures in the dataset are not singletons.
• Some structures in the dataset consecutively repeat.
• Some structures reappear in the dataset at regular intervals.