How much of the DPDT switch are you using? A relay is simply an electrically actuated switch, so obviously, a DPDT relay is an exact replacement...
If you are using all 6 terminals on the DPDT switch, you'd need 4 SPST relays (and two control signals) to do the same job. Or, with only one "signal" you sould use a 5th relay to turn-on the alternate pair of relays.
If you are only using 2 switch terminals, then an SPST relay will work fine.