Sorry, but I don't really understand your question, Sergey. Are you asking us if it doesn't matter how you pronounce 'ing'?

If that's what you're asking, here's an answer. If you can, you should aim for the standard pronunciation - ending with a velar nasal - rather than a regional variant. I certainly wouldn't recommend missing off the 'g' entirely.  There is a clear difference between how most native speakers say 'eaten' and 'eating', for example, and it would confuse listeners if you were to pronounce them in the same way.

But returning to your original question about adding an extra /g/ at the end...To be honest, I really wouldn't worry too much about this fairly minor aspect of English phonology. Most English native speakers are not actively aware of the difference between /ɪŋ/ and /ɪŋg/, so it really isn't an significant issue. 

According to your profile, your level of English is elementary ( one pink bar). If that's the case, you have far more important things to concentrate on.

It depends where they come from.

In large areas of the north-west of England, for example, the standard pronunciation is /ɪŋg/ with a clear 'g' sound after the nasal. A native of Manchester, for example, will say "singing" as "sin-ging" and "Hang on" in a way that sounds like "Han gon", with the voiced plosive connecting to the following vowel.

This isn't a new development, by the way.

.......

One point worth noting:

The silent /g/ after the velar nasal isn't always silent : it  reappears in comparatives.

For example, the 'g' is silent in 'long', but voiced in 'longer' and 'longest'.

I pronounce it like I am a bell.  So "ring", ping, ding, thing, wing