If there are no other grounds, tying the two earths together is appropriate and does not create a loop if I understand what the OP is describing. The tie wire should be the same type of ground strap used from the service panel.
Two physical grounds??
Due to construction issues the only way to ground my line conditioner is by instaling a dedicated ground rod for it (i.e. the house outlets are of type that accept a 2 prong plug). This dedicated ground rod for the line conditioner will be about 16 feet away from the ground rod for the electrical wiring for my house. By doing this would I get into trouble regarding a "ground loop".