IMHO the main reason for NOT using two inadequate calipers in the rear is, they are heavy and still ineffectual even when doubled up. Just because it's easy to do doesn't mean it's worth the effort. I can't be sure but I think Goran is only using the stock rear calipers for an easy solution to an e-brake- required for legal road cars. FWIW, stock Pantera rear calipers were also used on the Peugeot 205.
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