Based on your response, and the others that appeared after my post in
this thread, I may have misunderstood what the OP is attempting to
accomplish.  I assumed the following:
Server 1 (running production)
Client 1 (running production)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Server 2 (running some sort of a copy of the production database)
Client 2 (used for connecting to the copy of the production database
only)

Testing was needing to be performed by Client 2 against Server 2
without modifying the scripts or programs used by Client 1 against
Server 1.  There is a potential for problems with the above, just as
there would be with someone accidentally forgetting to change from the
default production connection string to the non-default test
connection string before dropping a couple tables.  The above change
limits the chances of someone asking - "oh, was I supposed to specify
a different database name" an hour after a conversion script starts
taking the "test" database from version X to version Y.

Joel, I trust your experience.  As you find the approach that I
suggested in this thread dangerous, I suggest that it be considered
that way, and not implemented.  Thanks for raising the red flag.

Charles Hooper
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.