When PM updates the file metadata (e.g., the caption) of tiff files with multiple sets of metadata in them, it only updates one set of data. This can lead to inconsistencies in the metadata.
The simplest case to reproduce this is as follows:
1. Let PM create a TIFF file from an image with e.g., the caption set.
2. This creates a TIFF file with two images embedded (a normal- and a thumbnail-sized one), as well as two sets off metadata (as can be verified with exiftool -a -Caption-Abstract; this will show you the caption twice).
3. Update e.g., the caption of this file in PM.
4. Only one set of caption metadata is updated (exiftool -a -Caption-Abstract will show you both your original and your new caption).
Apart from leaving the file in an inconsistent state (which is bad in itself), this is likely not a really big issue. It could, however, lead to software using out of date/incorrect metadata.
