The one voucher for the entire amount is for the 2016 taxes.
The other 4 vouchers are estimated tax payments for the 2017 taxes. So it the income stays about the same for 2017, then doing the 4 estimated tax payments would help so you don't owe again a year from now, or get an underpayment penalty.
If you don't want to do the 4 estimated payments, then just shred them and make sure you pay the taxes for 2016, by April 18, 2017 to avoid late charges.
