And it's not uncommon for devices to be mapped multiple times in the address space! The different aliases provide slightly different ways of accessing it.

For example, 0x000-0x0ff providing linear access to memory bank A, 0x100-0x1ff linear access to bank B, but 0x200-0x3ff providing striped access across the two banks, with evenly-addressed words coming from bank A but odd ones from bank B.

Similarly, 0x000-0x0ff accessing memory through a cache, but 0x100-0x1ff accessing the same memory directly. Or 0x000-0x0ff overwriting data, 0x100-0x1ff setting bits (OR with current content), and 0x200-0x2ff clearing bits.