This source (which gets several details wrong and appears to confuse Belgrade with Bilhorod and Sochi with Suceava) http://ocafs.oca.org/FeastSaintsViewer.asp?FSID=101582 was recently brought to my attention. I'm absolutely certain that this is the same saint as St. John the New of Suceava and so surely the two names should not appear on this page as though they were separate saints?
I would suggest that 'John the New of Sochi who suffered at Belgrade' is nothing more than a very poor, and confusing, translation of 'John the New of Suceava who suffered at Cetatea Alba'. It is particularly confusing as in English it implies two wholly diferent cities from the ones in which the martyr suffered and where his relics are, so I'd suggest that editting the page to remove it. I am slightly hesitant to do so unilaterally, however, as there is a small possibility that these are two separate saints in reality and that the OCA merely rather confusingly attributed the life of one to the other. I think the chance of this is very slim indeed, but it's sufficient to make me hesitant.