> Sounds like he's getting paid to work on the same thing by a slightly different stakeholder.

This honestly sounds like the sort of thing I'd sit down with the employee, their new employer, and various "Compliance Team" members, and firm up a bit.

Sounds good for everyone.

We get our bugs fixed, $vendor gets to say "Well we have this thing that was developed in-house for BoshNet, that might solve your problem too, it's going to cost you <some comical amount>", and everyone's happy.