here's a nice example of this type.
Aurelian and Vabalathus Billon Tetradrachm ( 21mm 9.2gm) Alexandria, Egypt. 270-271 AD. Obv: laureate, draped and cuirassed bust right of Aurelian, LA before (year 1 of Aurelian). Rev: laureate and draped bust of Vabalathus right, L- Δ across fields (year 4 of Vabalathus). Emmett 3914; SNG Copenhagen 898.
