can we use secondary respository backup in veema backup plugin for SQL server

You have to grant access to the repositories you want to use then follow this - Configuring Veeam Plug-in for Microsoft SQL Server - Veeam Plug-ins for Enterprise Applications

As noted on that site -

You can click Refresh to update the list of backup repositories. This may be helpful, for example, after you configure access to a backup repository and want to select this repository without the need to re-run the Configure Plug-in wizard.

Do you have licence added o use free version ?

as you said, the license installed on veeam server . need to require install on SQL server also for veeam plugin  ? right ?

No the main Veeam license should cover the SQL Plugin.

then how to resolve the second repository appear issue in Veeam SQL plugin.

Note - Please guide with proper solutions. 

if it is covered with main enterprise plus Veeam license, then you should send solution or alternate solutions.

Check the link I posted above for granting access to repositories as that covers what you need.