Iqtisodchilar metall pul turlarini ikki asosiy turga bo‘lishadi: yagona metall standart va ikki metall standart. Birinchisida asosiy pul birlik sifatida faqat bitta metall tangaga asoslanadi. Ikkinchisi, ya’ni ikki standartda esa oltin va kumush tangalarning ikkalasi ham asosiy pulni ifodalaydi. Ikki metall standart uchta sifatning mavjudligini talab qiladi:

Economists divide the types of metallic currencies in to two main types: the single metallic standard and the dual metallic standard. The first is where the main currencies are restricted to one single metallic coinage. As for the latter i.e. the dual standard, both the gold and silver coins represent the main currency. The dual metallic standard requires the existence of three qualities:

1. Oltin tangalar cheklanmagan qonuniy to'lov vositasi bo'lishi kerak (qat'iy xarid qobiliyatiga ega bo'lmasligi kerak).

1. Gold coins must have an unrestricted legal tender (no fixed purchasing power).

2. Ikkala metalning sofidan zarb qilishda hech qanday cheklov bo‘lmasligi kerak.

2. There should be no restrictions on minting from the bullion of both metals.

3. Oltin va kumush tangalarning qiymatlari o‘rtasida rasmiy kurs belgilanishi kerak.

3. An official rate between the values of the gold and silver coins must be established.

Ikki metalli standart shuni bilan xarakterlanadiki, unda bir vaqtning o‘zida metall tangalar asosiy pul birliklari sifatida ishlatilgani sababli muomalaga juda katta miqdorda pul chiqariladi. Shu sababli narxlar yuqori darajada qoladi, bu esa ishlab chiqarishning oshishiga olib keladi. Bundan tashqari, bu pulning qiymatini barqarorroq qiladi va narxlarda katta tebranishlar bo‘lish ehtimoli kamayadi, ular odatda iqtisodiy notinchlikka olib keladi. Shuning uchun ikki metalli standartni qo‘llash bir metalli standartdan yaxshiroq ekani aniq.

The dual metallic standard is characterised by the huge amount of money it puts into circulation, due to the simultaneous use of the metallic coins as main currencies. Therefore, prices remain high and this would lead to an increase in production. This would also make the value of money more stable and prices would be less likely to undergo major fluctuations which usually leads to economic unrest. It is therefore clear that operating a dual metallic standard is better than the single metallic standard.