Yes, use the AZ 309 (and the tag along 301). If you check the figures you should get a credit for the smaller of the AZ or CA tax on the income for the rental property, as a credit against the total AZ tax. This then eliminates the double tax and leaves the client paying the higher of the two state taxes, but not both. 

As with a regular return, you can claim any taxes PAID during the year to any state on the 1040 Schedule A. You will also get the privilege of claiming any refund you receive the next year, up to the benefit derived.