could be easilly done, but the major problem is for example that scenario:
You upload temp.pdf file on folder 1 with rights 1
Other user upload temp.pdf file on folder 2 with rights 2
In that case which is the correct option ? We've not implemented - by default - the kind of compacting repository by default because there's some problems like I exposed before that could have several solution and not all are valid to all environments ( user needs ).
Better option - I think - is planning the problem from other point of view. Better than make some option on uploading etc... I think it's better some mechanish that administrator could use to compating it. That could be done with two options, or combination both. First can be done some report with objective to list duplicate folder, and then make option you desire. Other option is some automatic task on scheduler.
That I think it's better solution than something made by default by OpenKM core, because, as I said, are several ways to solve it, but seems not all might be valid to all users.
The logic on a scheduler task could be:
1- Scheduler task executed each day
2- Search only files uploaded last day
3- Look if there's some file with same size ( if exist, then compare with it binary ) ( if it's equals then make some option )
4- Send mail to some users, about what task have done
( good option - better than delete - could be move that kind of files to some folder, and administrator then decide if want to delete or not, in you case seems you want to delete it directly .... then might be useful notify to user who uploaded that the files has been deleted because is duplicated and where's the file ). etc...
Obviously that needs some extra job - OpenKM parametrization / configuration - but with it the system will make exactly what you want.
Other solution, could be for example assign a workflow to all documents, and make it operation after uploading file, or using scripting for doing it.
I think workflow or task scheduler are more powerfull ways for doing it.
