DY, Writersoul,
I fail to see the monopoly issue that you are imagining.
You are saying that someone who is considering getting tested by someone else will not do so because if they are positive for something and they want to date someone who did dor yeshorim, then they will not be able to be re-tested by dor yeshorim, and that will convince them to not be tested by someone else to begin with.
However, people who are considering getting tested by someone besides dor yeshorim are not doing so with the intention to ever be retested by dor yeshorim, and are highly unlikely to know of this policy or to be considering it at all.
It is simply ridiculous to assume they are trying to target people whose intention was to be tested twice!!
Moreover, in your scenario the solution would have to be for the other person to be re-tested by an outside tester–which is a net loss of business to dor yeshorim, and the opposite of the intentions you ascribe. And this probably happens frequently, since people in the college world are generally tested by other organizations.
I changed my mind, you can go to a fake seminary after all.