Why do some Hindus say "ram ram" twice?, why not only once like "ram" or thrice like "ram ram ram"? What is the actual reason behind that?
Certain sounds are associated with some vibrations which enhance the functioning of Chakras of body.
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For example, Ram is the mantra for manipura chakra (navel centre) and if it is chanted in kirtan or repeated in japa, it will stimulate the abdominal area benefiting complaints such as peptic ulcer, constipation, diarrhoea and other digestive disorders.
Mantras Chakra Physical location
Lam Mooladhara Perineum
Vam Swadhisthana Base of the spine
Ram Manipura Navel centre
Yam Anahata Heart centre
Ham Vishudhi Throat
Om Ajna Eyebrow centre
For marathi people "Ram Ram" was Started by Samartha Ramdas in 1600. You can find the discription of these things in Dasabodha which is written by Swami Ramdas.So Whenever two person meet they greet as "Ram Ram".