Shell Programming and Scripting

My excuses for a Title which does not really describe what I need.
My OS is Windows Vista/Windows7
I have a large database of homographs with the following structure:

Code:

name=name variant

i.e. a variant of a name is provided on a line separated by a

Code:

=

.
An example will make this clear

Code:

John=Johann
John=Jean

Since the database has been manually prepared, it often happens that duplicates have been created where the left hand side variant and right hand side variant are inverted as in the example below:

Code:

Johann=John
Jean=John

This has created a database which is bloated because of these "inverted dupes".
What I need is a PERL or AWK script which will remove these dupes and keep only one set.
Example of Input and Output
Input:

Code:

John=Johann
John=Jean
Johann=John
Jean=John

Expected output after removal of dupes

Code:

John=Johann
John=Jean

Many thanks in anticipation for your help.

With 180 posts to the 59 threads you have started in these forums, we are starting to feel that rather than trying to learn how to use the UNIX-like tools available on Windows systems, you just want us to do your work for you.

What have you tried so far to solve this problem?

What isn't working with what you have tried?