Why does Arcmap 10.6 include files other than mxds in the recent file list? Was not an issue in 10.5.

[G_BRADFORDMARGESON]

I use Target for ArcGIS and recently installed ArcMap10.6.  Now Geosoft database files appear in the recent files list.  3 or more files load each time Target is used which takes up most of the recent file list.  This was not an issue in ArcMap 10.5.  What happened?