ADT7470 two byte I2C write supported?

ADT7470 datasheet rev. E says on page 10 that "In the ADT7470, write operations contain either one or two bytes".  When I try to do an I2C write with two bytes of data to the tach limit registers, I am seeing a NAK after the 2nd byte of write data.  Other places in the datasheet it only lists byte writes (Write Operations, p11-12).  Is two byte access supported?  If not what conditions would cause a nak on a write?

An example i2c write I see looks like this (adt7470 in bold):

<start><0x2c address><0 write><ack><0x62><ack><0xC1><ack><0x01><nak><stop>