Having 2 identities in a table
It looks like the comments may have answered this for you, but so there's an actual answer:

You cannot have two columns in one table that both have an IDENTITY(n,m) specification.

The most sensible approach for your requirement is probably:


your normal always-incrementing identity column should have the IDENTITY specification
use a SEQUENCE (see here for reference documentation and here for more general guidance) to control the other column that should reset each year.


You can restart a sequence on demand using 

ALTER SEQUENCE &lt;sequence_name&gt; RESTART WITH &lt;new_start_value&gt;;


This command could be issued in a number of ways, for example from a job scheduled to run yearly on your desired reset date.