Dray seems to occasionally split a group of moving particles (so far seen prot and grvt). All is duplicated in one frame but the postion of is of issue. half seem in the next frame while the previous exist in the last.
This occurs with and without Newtonian gravity.
edit: worked around bug by filling all particle ids before those of the dray (used bray as a temporary placeholder). All prot/grvt is forced to higher ids and are copied same.