None of the above.
Get a new one, and then glue it to the old one -- having cut the front cover of the new one off in order to fabricate the extension more seemlessly.
My latest was 8 of them, double-sided (equivalent 16), made into one. About 40% of side B remained blank, so I needed about equivalent 13 normal one-sided Spanish ones ; though my Camino was extraordinarily long, and the other double-sided French model given at SJPP is worth somewhere between 2 and 3 standard Spanish ones.
But, if you are a slow walker and starting at SJPP -- get two, glue them back to back, and that will easily be sufficient. Probably three or four Spanish ones arranged similarly would be sufficient too.
You only need more than that if your projected Camino distance is in the 1,000s rather the 100s.