WI: Valerian defeats Shapur

IOTL, roman forces clashed with sassanian persian forces at the Battle of Edessa, in 260 AD. The persians ended up winning, and even captured the roman emperor, Valerian, who was held captive by the persian king Shapur until his death.
So, what if the battle had a reverse outcome, with Shapur being defeated and discredited, and Valerian pulling out unscathed?
It seems to me that Valerian had delegated control of the empire's western provinces to his son and heir, Gallienus. Could an earlier division of the empire be made?
 
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