137.08 Sums for which sureties may be bound.—In every bond in which the amount of the bond shall not exceed $1,000, there shall be at least two sureties, each bound for the full amount of the bond. In every bond so specified in which the amount of the bond shall exceed $1,000, each surety may bind himself or herself for a specified sum, and the aggregate amount for which the sureties shall bind themselves shall not be less than the penalty of the bond.