My informant who provided the sordid details about the White House ceremony at which the Army Herald Trumpets and the US Marine Band played Hail to the Chief out of sync with each other and in different keys--described in the post below--has learned how things went so wrong.
According to a highly-placed Washington, DC source, the Army's Herald Trumpets always perform the presidential honors at White House arrival ceremonies. The Herald Trumpets know this. The president's staff knows this. Anyone who has ever studied for the MU2 test knows this.
The coordinator from the Marine Band didn't know this. He didn't attend the dry run, didn't even attend the talk-through rundown of the ceremony.
Fortunately the bands were spaced far enough apart that most attendees, including the president, were unaware that honors music was being performed by two bands in two locations in two keys.
Not doubt this was followed by a smaller, more private ceremony in honor of the Marine Band's coordinator at which the honors were performed on muffled drums.