Booting of NS9750

How does Ns9750 boot. It is said that Chip select 1 is mirrored with chip select 4 and chip select 0. Does that mean that when chip select 0 is asserted, chip select 1 will also be asserted. Will this not create a confusion for the devices which are hooked on to these chip selects.(ie) two devices will get simultaneous get chip selects and cause a bus contention.

Kindly help me understand this feature.