Since ASIO device names can be very long, vMix automatically shortens the name by removing what is the same in both channel names.
This is why you get this result in some cases where the first number matches in both.

This unfortunately cannot be fixed due to the complexity involved in checking and making sure certain parts of the name are not compressed, and the potential other unintended side effects of doing so.

That said, the solution is easy, simply set the name of the input to whatever you want manually after creating it.