Even the dear the old JP was side by side, though no rocket pack, it was a purely gun seat, so no rocket plume, as I suspect is at least one type on your list (the B52?) There was presumably a risk of mechanical interference between the seats on ejection if you went purely simultaneously but no one ever really mentioned it.
As far as seats with rocket packs, firstly on all the ones I knew of the rocket didn't fire until the seat was well up the rails thanks to the gun which gave the seat the initial push.. I however do know of an almost simultaneous double ejection on an F4 (obviously tandem rather than side by side but as a crew you are still quite proximate) with the pilot just going first and as a result the nav suffered superficial burns from the rocket plume from the pilots seat as they both left the aircraft in very close formation with the nav trailing the pilot...not nice for the nav but he certainly wasn't eviscerated.
Last edited by wiggy; 11th Feb 2017 at 08:47.