Actually there is already "confirm password" field, you can try to activate it via Developer app. But there are several "confirm password" fields, make sure to activate field "password_confirm" name, you can see the field name during field editing.
Thanx alot, Alex, it works :))
NB for those who can't find
1. Look in Developer/Forms/System - than Choose_field/Account/Create_account
2. It have to do in Developer, because in Forms app there is no option to enable this field.
