Error: VAT + VAT charged on checkout

[enigma666666]

Hi guys, my client alerted me to a strange error that started appearing on his store and I dont have a clue as to how to find the solution to this problem.
The VAT charge is supposed to be a once off 14% on total during checkout and has always functioned correctly until now.

Customers are now being billed twice for VAT!
This is how it looks on the invoices:
Sub-Total: R342.24
Shipping (5%): R17.11
VAT 14% + VAT 14%: R100.62
Total: R459.97

Under the heading "tax" on the invoice it says 28.00% which is obviously wrong.

Any ideas as to why things are now displaying wrong all of a sudden?
Ive looked at tax zones and definitions and everything seems to be in order.