The simple answer is that it used to be a colony of Spain and used the Spanish monetary unit which is the Peso as well.
In the early 1900's the U.S.A. took control of the Philippines and established the unit of currency as a "gold peso" which was supposed to be 1/2 the value of a U.S. Dollar.
The Japanese occupied for a while as well, but the Peso has stuck as the monetary unit
There is not now and never has been a "British dollar." Britain uses the Pound Sterling as its primary monetary unit.
Chinese monetary unit - the monetary unit in the People's Republic of China monetary unit - a unit of money kwai, yuan - the basic unit of money in China jiao - 10 jiao equal 1 yuan in China fen - 100 fen equal 1 yuan in China
Inflation has a lot of impact on monetary unit assumption. Inflation greatly reduces the value of a monetary unit and acts as a hidden tax on consumers.
Kwanza
krone
The Philippine monetary unit is spelled as "peso."
Monetary unit: Colombian Peso
The Colombian Peso (COP) is the monetary currency of Columbia.
Peso Argentino
The Mexican currency is the Peso.
The unit of money in the Philippines is called the Philippine Peso, abbreviated as PHP or ₱. It is further divided into 100 centavos.
The Mexican Peso (MXN).
There is not now and never has been a "British dollar." Britain uses the Pound Sterling as its primary monetary unit.
The Mexican Peso.
The currency of Chile is the Peso. It is an abbreviated with CLP.
centigrams
Cuba's monetary unit is known as peso. As of July 2014, one US dollar is equivalent to about 23.15 Cuban pesos.