Perhaps the other guy wasn't killed, though I suppose the other guy could have been killed & may be buried in a non-government related cemetery (which would result in him not being in the ABMC & the National Gravesite locators).
Multiple seems to suggest a daisy chained style grouping of mines, i.e. one soldier steps on a mine, which is connected to other mines. When that mine detonates, so do the others (or they can detonate in staggered timings, though I do not recall if they had those in WW2). It could also have had an added, improvised explosive as well. Who knows. The various pretty much stuck anything in the ground that would maim or kill back then (how times haven't changed...). Such a chain of mines could easily take out a couple of soldiers and do some horrific damage, particularly if the timing was staggered for the chain. A mine could have killed him and another nearby could have wreaked further destruction on his remains. Hrm.
That site may not have all the docs for the unit though. Perhaps there's a morning report with more info...
HR