Those shields went up over a decade ago and have generally been covered, but in many cases the cover fell off the sign. I'm going to assume "the cover fell off" given the lack of an announcement or AASHTO application. This is different from the I-81 concurrency in that I-81 was just a matter of slapping a second Interstate designation on an existing Interstate.
There are a few other places along 17 with covered I-86 shields, most notably Tioga and Sullivan Counties. I don't expect any movement in Orange/Sullivan until the upcoming reconstruction project is complete.