Can a Cleric in the Realms serve two Dieties w…

Can a Cleric in the Realms serve two Dieties with the same Domain?

Can a Cleric in the Realms serve two Dieties with the same Domain, say The Red Knight and Valkur, Exarchs of Tempus, as they are both gods of Strategy, one of Strategy and the other of Naval Combat with the War Domain.