Yes, maybe a student work or a sketch or something, kept in a drawer somewhere. It’s rather irritating when things like that happen; when there is no trace whatsoever of a violin concerto no. 1.
Same with Goldenthal. He did a “Symphony No. 3” in 2021, but there is no 1 and 2. You’ll have to surmise that No. 1 is the “Symphony in G Minor” and 2 maybe the OTHELLO symphony, which was an adaptation of the ballet score.
But I can’t find anything, named differently, that would be No. 1 in Holdridge’s canon.