I don't want to delete duplicates, I want to replace duplicate files with UNIX style had links.

Does anyone know of a program that will find duplicates and replace them with UNIX style hard links?

When compared to other comparison utilities - Chipmunk is sorely behind the pack. Program has no contextual menus, lacks ability to reveal duplicates it finds, and its documentation is poor. It is faster than the other comparison utilities but users will want to "quick view" files to make sure they are really duplicates and Chipmunk provides no way to do this (even via the Finder). Each duplicate needs to be exposed by clicking on a "drop down" triangle - there is no way to "Select All" or "Select Multiple" to expand more than one at a time - Printout of the duplicates only mirrors exactly what you have expanded, listings are clipped with regard to long file names/paths in output. HIghly suggest looking at Tidy It Up which is $30 - well worth the $10 cost.. Chipmunk also crashed during my evaluation - requiring rescan of directory/hard drive. On the Positive side - the graphical interface to the directory tree is pretty cool - as to selecting whether to eliminate duplicates outside of the node or within the node - but again - even the procedure for this is not really clear in terms of the online help.. I think it is a good start for this type of program - but it is too highly priced for its very very limited capabilities.

1) did compare creation and modification date.
2) could not find a get info or reveal in finder