By law both currencies can be used interchangeably, so if you're coming in from Singapore, there's no reason to change money as your cash will be readily accepted.
Sharci ahaan lacagaha waxaa loo isticmaali karaa si is dhaafsi ah, marka haddii aad ka soo galayso Singapore, Ma jirto sabab loo beddelo lacag maadaama lacagtaada caddaanka ah si fudud loo aqbali doono.