How to process payment to vendor and with-holding tax vouchers

[kwaku emm]

In my country when a purchase is made, an amount of with-holding tax is taken from the total amount to be paid to vendor. The deducted amount is then paid to the tax agency. 2 payment vouchers are created for both entities. my questions are
1. Are they 2 transactions or just a single transaction.
2. How do I record such a transaction?
3. Should the two payment vouchers be given the same number? or different numbers?
Thanks.