You can find the markers by either doing it in a brute force manner using the Find > Marker of type (and have the Marker window open to see the contents) or by using a MIF version and using a text editor to search for the MText right after a <MType 9> entry. The MText would be the duplicate and the Unique ID entry would be two lines further.
The general structure of a Marker in MIF is as in the following example:
<MText `37042: Body: At vero eos et accusam et iusto odio blandit praes'>
> # end of Marker
Cross-refs target the MText line using a <XRefSrcText ...> entry that is the same as the MText content.