iPad Files App replacing/duplicating existing documents with other documents

Hi all,

Recently my iPad Pro Files app began replacing the content of one document I was working on with the content of another, right down to the highlighting and annotations done in the other document. The original file name remains the same, but the content is the same as the content in an existing document. The document that was replaced is nowhere to be found.

This has happened twice now and I have lost hours of annotated work for no reason. What could cause this? Any tips to fix?