Complex sentence: In Guernsey, the penny (1/240 of a pound) was subdivided into 8 "doubles", with coins issued in denominations of 1,2,4 and 8 doubles.
Split into simpler sentences: In Guernsey, the penny (1/240 of a pound) was subdivided into 8 "doubles". Coins were issued in denominations of 1,2,4 and 8 doubles.