That's OK John. Don't worry about it.
You can see the interface. between the 2 materials. It is not usually very high in amplitude, but is there, nonetheless. That's why I recommend using an experienced UT technician.
You have to know what signals to use. Now, I can't guarantee the accuracy, because SS316 wrought material (cal block) has a different velocity than SS cladding, which is basically a casting. Same as a weld. Velocities are dfferent everywhere and in all directions.
But it should not adversely affect a 0 degree L-wave at the proper frequency, and can be done as long as there is a reasonable tolerance for remaining thickness.
Ideally, a mockup with 316 cladding to 516 steel would be manufactured with the cladding applied in the same manner as the component to be examined with flat bottom holes or square notches in the cladding at various depths and used for calibration.