Can i swap dual port exhaust manifolds on a single ej22 98 impreza engine?

It is theoretically possible to swap the single-port exhaust manifolds for dual-port exhaust manifolds if they are from same model EJ22 engines.

Both your original exhaust manifold and replacement dual-port manifolds should mount on the cylinder heads in the same way and it should connect without problem with exhaust pipe on the turbo. Some minor adjustments or customisation might be needed, but overall these parts can be compatible to use.