I like all the explanations given by Denis, I believe they are predicated upon strong grounds. But frankly speaking, I’m sure that most of homonyms are such not because of some deep-rooted cause, more likely a simple chance underlies the spelling identity of semantically different words.

Soumyajit, to continue speaking about Russian homonyms (and not only of them) I’d like to propose you a riddle. Try to translate a very short dialog:

Михаил: Дорогая, ты будешь кофе?

Светлана: Да нет наверно…

This is a very typical sample of informal Russian speech. Do you understand what really Svetlana answers? “Yes”, “no” or “may be”? Russian native speakers, please – no prompting!!! ;)))

 And can't help recalling this:

 How much wood would a woodchuck chuck if a woodchuck could chuck wood?

Soumyajit, why do you wonder? Homonyms are usual in any language. English has a lot of them too:

How much can a bare BEAR BEAR?

A LEAN cat could LEAN on a skunk!

Why don't we TOAST with a TOAST?

blind as a BAT; a baseball BAT; not to BAT an eyelid

a rock BAND; a rubber BAND

the BANK of the river; the BANK of England

a CUE to stop; billiard CUE

to tell a LIE; to LIE on the floor;

what do you MEAN? it was MEAN of him to say it; MEAN speed

the SOUND of music; a SOUND mind in a SOUND body

corn STALK; to STALK a deer

very WELL; a deep WELL

and so on...