We separate supplier IDs by physical location they are shipping from, so even if the same tax code, we would still created two different supplier IDs, especially if there are different products coming from each different facility.  Now if they were co-located within the same town or city, that might not be necessary.  However, one of them would need picked as the main one for invoicing/payment, then the other could be connected to the main one.

The idea with the second or multiple address IDs is more for when there is a distribution or shipping warehouse location for them - this would be the main visit ID.  But there might be a separate address which is where they want the payment sent - the pay address ID.  If there were yet a separate corporate address, then the document address type would be used.

We always let the type of address drive how many address IDs are needed, if the Pay, Visit, Delivery, and Document are all the same address, then we set only one address ID and all four default types.

But if one of the address types are different, then we add one or more additional identities to separate by type.

thanks for the quick feedback,

so if we have 1 supplier who has 2 addresses, the second address is used for invoicing, then what we will have in this case, is the first address with all boxes checked except PAY, which will be checked for the second address, right ?

and in this case, we will be having 1 supplier ID , with 2 addresses, first address for DOCUMENT, VISIT, DELIVERY, and second address with PAY checked

Yes, that is the way we would setup the account for your scenario.  One Supplier ID with 2 address and the Address Type split per address ID according to their use.  This is the most efficient method we have found to prevent duplication of information for what is the same physical location and legally defined entity.