Ground Truth Label Jobs - Same document repeating in the labeling job

We want to extract the entities from pdf documents. We are exploring labeling the existing document using Safemaker GroundTruth. The documents are keep repeating for some reasons which we are not able to identify the reason ? When it repeats some pages coming as read only and other pages will us to annotate. When it repeats the previously read only pages are annotable .

Can some expert from this help us to understand why it is repeating ?