When referencing Marked Points between oriented photos a ‘ghost’ helper line will be displayed for each photo the selected mark has been referenced on. The technical term for this line is the epi-polar line. The matching location on the destination photo should lie somewhere along these lines, likely near the intersection of them if multiple are shown. The better the orientation of the source and destination photos the closer the lines will be to the true location. You should always mark and reference the points at their true location on the photo even if this location conflicts with the helper lines, since the reference helper lines are just a guide to help locate the general area on the photo to mark.
A source and destination photo showing a source mark that has not been referenced yet (i.e. is only marked on that one photo so produces a single reference helper line):
A source and destination photo showing a source mark that has been referenced on 3 oriented photos, the point location should be where the reference helper lines intersect:
When referencing points or silhouettes, if a mark already exists near the reference helper lines the potential matches are highlighted (see Reference Helper Highlight).
The visibility of Reference helper lines on photos can be toggled using the Show/Hide Reference Helper Lines tool on the on the ribbon toolbar’s Create Tab (Referencing group). You may want to hide them when several are showing and possibly obscuring the point on the photo to be referenced.
Note you can also set the maximum number of helper lines to appear on the Preferences dialog, see Preferences - Marking and Referencing.