Corrupted Block 'Table' in V8?

I appear to have a V8 file with a pair of external Blocks that have somehow become linked inside the file I’m working on.

They are both simple external Blocks created in Rhino V5 that have been inserted as linked and embedded in the V8 file. Each consists of nothing more than a polyline outline and a png PictureFrame image which in both cases has been embedded in the respective V5 file using the old TestSuck… command. They represent nothing more than images of labels.

Opened separately in V8, they behave as they should. In the file I’m working on, they both show one or other PictureFrame image, but not both. If I explode one Block and navigate to the correct png image, all instances of both Block types change to the picked image. The two Blocks have different names.

Any suggestions as to what I can do to fix this problem?