clone activity replicates an arrival n times (the original
one + n-1 copies). A synchronize activity removes all but one clone.
clone(.trj, n, ...)
synchronize(.trj, wait = TRUE, mon_all = FALSE)FALSE, all clones but the first to arrive are removed.
if TRUE (default), all clones but the last to arrive are removed.TRUE, get_mon_arrivals will show one
line per clone.