参考MSDN的解释:
For example, the Publisher could be assigned the range 1-100, Subscriber A the range 101-200, and Subscriber B the range 201-300. If a row is inserted at the Publisher and the identity value is, for example, 65, that value is replicated to each Subscriber. When replication inserts data at each Subscriber, it does not increment the identity column value in the Subscriber table; instead, the literal value 65 is inserted. Only user inserts, but not replication agent inserts cause the identity column value to be incremented.
发布的和用户自己增加Identity的值是不同的机制。
http://technet.microsoft.com/en-us/library/ms152543.aspx