Were there many? I've come across a newspaper report of three men, all St. John Ambulance Brigade members, who were awarded both medals.
"Three members of the local St. John's Ambulance Corps have been awarded the China medal. The lucky men are:
117 Private S. Kingston, of Northampton;
130 Private Beeby, Kettering; and
1,482 Private F. W. Green, Wellingborough.
These are the only three gentlemen in the whole county who have been honoured with this particular decoration, which will be handed to the recipients, we understand, by Captain W. Hughes, the Chief Superintendent, at any time now. An inspection of the medal reveals a slightly and deep-struck silver token, bearing her Majesty Queen Victoria's effigy and a device of arms with an appropriate Latin scroll. The ribbon and medal when they appear at parade in the future will be a rare distinction. The men in question, it is interesting to note, all served in the South African campaign, and upon coming home again took their discharge. When the China trouble arose, however, they were among those who volunteered. They were selected, and served on the special hospital ship Maine. They already have the South African medal, so that the authorities in these cases leave no ground for a murmur as to grudging recognition of brave service eagerly undertaken."
The Northampton Mercury, Friday 31st July 1903