The only two QF aircraft going through are QF2 LHR-DXB-SYD and QF10 LHR-DXB-MEL. They arrive 1hr apart. (QF1 and QF9 do the reverse and are similarly spaced, but different time of day).

The aircraft are swapped at LHR when required, I think it would be extremely rare for them to swap at DXB. Even then, a large proportion of passengers are through passengers as well, and the two are normally at nearby gates.