Agree. It's a similar issue. Looks like the solution you suggested is not implemented yet.

I have found another workaround though. Let both the taxes fall in the same group and same type. That means when creating a PO both taxes will apply. Just add a note in the memo that only one will be used on invoicing.
When the items are received and invoiced, the tax amounts are editable - so make the one which is not applicable 0. That way there are no duplicate items or vendors and the taxes also reflect the right amount.

Let me state the problem again.
How do I apply a tax of 14.5% OR 2% on Item 'x' from Vendor 'a' without having to create two separate items or two different vendors?
Please note at a time only one of the tax will apply.

I don't think that will work until you can assign two tax groups to the same supplier. Take a note of what is required below:
For the same item and same supplier we can have 2 different taxes applied - how to handle this in FA ?

This is a practical scenario we have to handle. In India when we buy an item from a supplier the tax he applies can be VAT of that state or CST of 2% depending on whether we submit a certain document to him or not. So as an example if we buy a PCB from somebody in Karnataka he will normally charge 14.5% VAT but if we produce a document (C-Form) then he will charge only 2%. Typically the document is produced only for large purchases.

This means for the same item and same supplier we can have 2 different taxes applied - how to handle this in FA ?

If this is not possible then has somebody worked around this ?