Replication Subscribers and AlwaysOn Availability Groups (SQL Server)
The first problem:

Error 21488


  No active subscriptions were found. The publication must have active subscriptions in order to post a tracer token.


This happens when attempting to put in a tracer token without an active subscription. This error seems pretty obvious.

Error 18752


  Only one Log Reader Agent or log-related procedure (sp_repldone, sp_replcmds, and sp_replshowcmds) can connect to a database at a time. If you executed a log-related procedure, drop the connection over which the procedure was executed or execute sp_replflush over that connection before starting the Log Reader Agent or executing another log-related procedure.


Make sure there are no other logreader agents running for the same publishing database.

Second part:


  Second problem- How to maintain primary key value to avoid conflict between publisher 1 and publisher 2 to sync with node-1 because database are same ??


You'll either need to add a unique field (such as servername, etc) or configure some way of making each record unique. Generally, if not designed for at first, will require a schema change. Commons solutions are to use even/odd numbering in identity columns/id fields or using the source host name/database name.