Everything is in the title, sorry if I misspelled it.
Why do Russian speakers call Vladimir Putin "Vladimir Vladimirovich" ?
A full Russian name consists of:
Patronymic (derived from father's first name)
Last name, also known as family name.
Russian president's full name is: Vladimir (first name) Vladimirovich (patronymic) Putin (last name).
The following combinations of names are used in a formal environment:
First Patronymic Last - Vladimir Vladimirovich Putin - very formal
First Patronymic - Vladimir Vladimirovich - moderately formal
First Last - Vladimir Putin - moderately formal, the same level of formality as #2.
More information on the order of Russian names is available here: What order are the parts of a full Russian name in?