A commandline tool with the following synopsis is introduced:

usage: deduplicatecontacts
-A,--adminuser <arg> Admin username
-c,--context <arg> A valid context identifier
-e,--execute Actually performs the de-duplication of contacts.
By default, identifiers of duplicated contacts are
printed out only.
-f,--folder <arg> A valid contact folder identifier
-h,--help Prints a help text
-l,--login <arg> The optional JMX login (if JMX authentication is
-P,--adminpass <arg> Admin password
-p,--port <arg> The optional JMX port (default:9999)
-s,--password <arg> The optional JMX password (if JMX authentication
is enabled)
Handle with care and review the found duplicates before executing the
de-duplication. Detected duplicates are deleted permanently, with no
recovery option.