Hydro
Night or day ?
Were they travelling horizontal or vertical or across the horizon so to speak.
Reason I say is one aircraft makes the noise and flares create the other lights,
If of course it was at night. Flares last 30 - 60 seconds and are often fired in 2 - 3's.
Wagga is an army training area, especially in 1991.
You get some amazing patterns.